fix(showcase): remodel broadleaf-oak as a massive mature oak with a cushioned leaf-mass crown

The oak read as a sapling with giant paper leaves: 0.54-0.70 m leaves (5-6x
real) in thin clusters, a flat-topped umbrella of see-through sticks, a
slender trunk for its crown and a tiny grass patch. It is rebuilt:

- trunk: DBH 0.73 -> 1.11 m, fork 2.30 -> 2.15 m, 84 sides (was 36), eight
  broad flutes and 21 bark plates with broad flat tops and narrow deep
  furrows that wander and fork up the bole (bark_plate); a Furrow point
  attribute darkens the furrows; ridges carry over the fork dome; buttress
  flare 0.44 -> 0.72 m; seven roots (was six), thicker and half out of the
  soil
- limbs: each segment kinks the other way from the last (zig-zag); the two
  lowest scaffolds reach out sideways to the hero nearly level and dip,
  steep ones alternate with them round the bole (SCAFFOLD_YAW0, fixed
  elevation order, was shuffled); branching 3,3,2 (155 branches, was 260)
  so gaps show the limb structure; twigs take 0.7 of the child share
- crown: 295 leaf-mass cushions. A hidden jittered-cube core holds each
  carrier (every live branch end, and rings along the outer part of every
  branch that carries twigs, widened round thick limbs); 2075 faceted leaf
  clusters (20-tri jittered icosahedra) are centred in the cores; 618
  lobed oak leaves (24 tris: three lobes a side and a terminal lobe, 0.24-
  0.32 m, ~2.5x real) sit on the outer clusters. A new OakCanopy material
  gives each leaf-sized Voronoi cell its own green and its own tilt of the
  shading normal; custom split normals (out of the cushion 0.6, out of the
  crown 0.4) shade clusters as one billow instead of as balls. The plan
  places every leaf and cluster against its host's built skin, read by a
  ray over both splits of each quad
- ground: soil disc 2.55 -> 4.40 m half-axis, now a mound heaped 0.12 m
  over the root flare; last year's leaves drift in the turf shader round
  the bole; 70 fallen leaves, 12 acorns, four sticks (two forked), 20
  taller tufts
- camera 24 -> 29 m, wall 9.5 -> 10.5 m; key 5150 -> 7200 W, fill 760 ->
  1150 W, wedge 1720 -> 2100 W, world 0.045 -> 0.031, so warmth sits back
  inside the calibration spread

Drafts rejected on the way (all looked at): cores alone with leaves read
as green balls with a turtle-shell pattern; 3000 leaves with no mass read
as a sapling again; big smooth cores read as topiary pom-poms; cube
clusters read as Minecraft blocks up close. A cluster is ~10x the canopy
per triangle of a leaf, so the budget went to clusters, leaves to the
silhouette.

Budget changes:
- Base tris 67700-69000 -> 86250-87150 (measured 86700, 69% foliage:
  45040 clusters and cores, 14832 leaves; LOD 0.4995/0.2167)
- 8 -> 9 materials (canopy); face floors re-fit (7481/14832/256/1566/
  1276/2734/2880/1680/43270 measured)
- Outer AABB -> (11.529, 11.716, 8.958) m; DBH 1.110 +- 0.02
- Bands narrowed to the new measurements: seat >= 0.10 (0.1926), area
  0.94-1.02 (0.9697-0.9898), child <= 0.72 (0.6560), fork 0.78-0.90
  (0.8347), nut 0.005-0.013 (0.0090), balance <= 0.30 (0.2148, now over
  leaves and clusters), roots >= 0.020 (0.0437), stalk >= 0.010 (0.0204),
  tufts 0.045-0.080 (0.0588-0.0647)
- Exit 22 is now three sub-budgets: cushion core holds its carrier
  >= 0.040 (0.0543), cluster centroid in its core >= 0.010 (0.0176), leaf
  petiole in its cluster >= 0.010 (0.0195). A first cluster measure (deepest
  vertex of either lump in the other) read -0.09 for plainly overlapping
  lumps (thin core through a ball); the centroid depth replaced it
- --perch-trunk: on the level mound the old foot still sealed 8/8 (exit
  0), so soil is heaped over the flare and FOOT_OFFS -0.060 -> -0.045
- --shed-leaves pushed outward grew the envelope 0.11 m (would exit 8);
  it slides inner leaves toward the crown's centre instead

Falsifiers (flag -> measured -> exit), 5.2.1 and 4.5.11 identical; tris
86700 and AABB unchanged in all:
  --skip-decimate     LOD1 1.0000                               9
  --stray-vert        loose_v 1                                15
  --lift-z            zmin 0.05000                             16
  --float-branches    seat -1.5494 of parent radius            17
  --pop-nuts          nut in cup -0.0248 m                     18
  --lean-crown        lean 2.908 deg                           19
  --fat-twigs         area 1.7240, child 1.0413                20
  --perch-trunk       sealed 0/8                               21
  --arch-roots        root station -0.1555 m                   21
  --orphan-clump      carrier in core -0.1063 m                22
  --scatter-clusters  cluster centroid -0.1894 m (new)         22
  --shed-leaves       petiole -0.8680 m (new)                  22
  --drop-acorns       pedicel in cup -0.0491 m                 23
  --float-cover       100 shells loose, tufts 0.0010-0.0047    24
tests/check_falsifier_targets.py --run --only broadleaf-oak passes.

Evidence (live runs, local):
- .scratch/5.2/blender-5.2.1-windows-x64/blender.exe (Blender 5.2.1 LTS):
  two default runs identical; hygiene 0 incl. 0 coplanar cross-shell
  pairs; collider 54; export 10351880 B.
- .scratch/blender-4.5.11-windows-x64 (4.5.11 LTS): all 15 runs same codes
  and values; measurements identical except LOD 0.5000/0.2200 (+20 B glTF).
- .scratch/blender-5.1.2-windows-x64 (5.1.2): default exit 0, same.
- Framing: fill x 0.534, y 0.850; margins l .222 r .244 b .056 t .094;
  asset-quality floors pass (9 materials, edge90 0.034).
- Contact sheet: luma 0.2383 (band 0.2369-0.2428), stage 0.2514 (0.1919-
  0.2517), warmth +0.0907 (spread -0.144..+0.105; was +0.1092), sat
  0.1696. Thumbnail: a broad domed oak on a heavy trunk.
- Asset sheet: before, a bushy sapling of big paper leaves; now a mature
  oak with a massive buttressed trunk under a dense, lumpy dome. Not the
  least-designed object (the hydrant is plainer). Weak point: up close
  the clusters are visibly faceted low-poly lumps.
- build_gallery, check_site_links (122 pages, 0 failures), check_engine_id,
  check_exit_code_readme, check_gallery_images, check_import_export_rules
  pass.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: TMHSDigital

README.md

@@ -172,7 +172,7 @@ Budget-conformance props. Not examples. Conventions: [`showcase/README.md`](show
   <a href="showcase/traffic-cones/"><img src="showcase/traffic-cones/preview.webp" width="24%" alt="Traffic cones: orange cones with white reflective collars on a patch of asphalt with a worn white line, three standing in a row, three nested in a stack and one knocked over showing its open base, before a striped A-frame barricade with an amber warning lamp" /></a>
   <a href="showcase/mushroom-stump/"><img src="showcase/mushroom-stump/preview.webp" width="24%" alt="Mushroom stump: a sawn tree stump with a stepped felling cut and torn hinge fibres, peeled bark with curling flakes, moss, banded shelf fungi, honey mushroom clusters, red fly agarics, ferns and fallen leaves on a sloping soil disc" /></a>
   <a href="showcase/go-kart/"><img src="showcase/go-kart/preview.webp" width="24%" alt="Go-kart: yellow go-kart on a patch of track asphalt before a red and white kerb: bent red tube chassis, black seat, finned engine with chain to the rear axle, slick tyres on silver rims." /></a>
-  <a href="showcase/broadleaf-oak/"><img src="showcase/broadleaf-oak/preview.webp" width="24%" alt="Broadleaf oak: a broad oak with a short fluted trunk and crooked spreading limbs under a domed crown of lobed green leaves, on a grassy soil disc with surface roots, tufts, fallen leaves and acorns" /></a>
+  <a href="showcase/broadleaf-oak/"><img src="showcase/broadleaf-oak/preview.webp" width="24%" alt="Broadleaf oak: a mature oak with a massive buttressed trunk and crooked limbs reaching out under a broad dome of lumpy dark-green leaf cushions, on a grassy mound with roots, tufts and fallen leaves" /></a>
   <a href="showcase/farm-tractor/"><img src="showcase/farm-tractor/preview.webp" width="24%" alt="Farm tractor: green farm tractor in muddy ruts beside a puddle: long bonnet, barred grille, rusty exhaust stack, big lugged rear tyres on cream rims with weights, small ribbed fronts." /></a>
   <a href="showcase/fern-mossy-rock/"><img src="showcase/fern-mossy-rock/preview.webp" width="24%" alt="Fern and mossy rock: a male fern's arching crown of finely cut fronds, with curled fiddleheads, in front of a cleft boulder cushioned in moss on a soil bank with fallen beech leaves, pebbles and wood sorrel" /></a>
   <a href="showcase/sea-stack-arch/"><img src="showcase/sea-stack-arch/preview.webp" width="24%" alt="Sea stack and arch: a layered sandstone sea arch on a wave-cut rock platform, a sea stack beside it on its own island, foam at the waterline, fallen blocks, and grass and pink sea thrift on the tops" /></a>
@@ -300,7 +300,7 @@ Budget-conformance props. Not examples. Conventions: [`showcase/README.md`](show
 
 [`go-kart`](showcase/go-kart/) — the eighth `vehicles` piece: procedural rental go-kart on a patch of kart-track asphalt against a red and white kerb (a 30 mm tube chassis whose main loop is one bar swept round every bend, cross tubes ending inside the rails with welded gussets, bearing hangers and kingpin C-brackets; spindles on kingpin bolts with 14° caster; a three-spoke wheel on a raked column in a bushing, a steering plate and two tie rods on rod-end eyes; a bolted nose, side pods on nerf bars and a curved front panel; a moulded seat on stays, a floor tray, two pedals, a strapped fuel tank with its line and a lead ballast block; a finned four-stroke clamped to the right rail with a pull-start, air-box and silencer, driving the live rear axle through a clutch, an 88-link chain solved to a whole number of pitches and a 60-tooth sprocket; bearing carriers, a brake disc and caliper; a tubular rear bumper; four loaded slicks on split rims with valve stems, the fronts narrower than the rears), whose tyres pressed into the asphalt in one plane, hubs and bearings coaxial with their axles, tie-rod eyes on their pins, tyre beads and chain seated, frame, bodywork and wheels mirrored at the stated wheelbase and tracks, caster, mass centre inside the support polygon and one connected assembly are recomputed from the mesh, through the same pipeline. `--float-tyre` exits 16 on every tyre grounded, `--cock-hub`, `--drop-bearing` and `--short-tierod` 17 on joint fit, `--sink-tyre` and `--lift-chain` 18 on the bead and chain seats, `--toe-wheel`, `--wide-track`, `--odd-frame` and `--no-caster` 19 on mirror, size and caster, `--aft-ballast` 20 on the stance, `--loose-ballast` 21 on one connected assembly, while the envelope holds.
 
-[`broadleaf-oak`](showcase/broadleaf-oak/) — the eighth `nature` piece: procedural mature, open-grown English oak on a sloping grassy soil disc (a short fluted, ridged trunk flaring through six buttresses into surface roots bedded in the soil, a low fork into five crooked scaffold limbs that divide three more times into 260 tapered branches, each seated in its parent and narrowing past every junction by its child's area, a broad domed crown of 1370 lobed oak leaves in clusters on every twig tip, dead twigs, acorns with scaly cups and glossy nuts hanging on stalks and lying in the grass among curled fallen leaves, tufts and sticks), whose branch seats, da Vinci taper, nuts seated in their cups, plumb trunk and balanced crown, foot and roots sealed in the soil, leaves carried by their twigs, acorns hung on their stalks and ground cover joined to the soil are recomputed from the mesh, through the same pipeline. `--float-branches` exits 17 on every branch seated in its parent, `--pop-nuts` 18 on every nut seated in its cup, `--lean-crown` 19 on plumb and balance, `--fat-twigs` 20 on the taper and area rule, `--perch-trunk` and `--arch-roots` 21 on the trunk and roots sealed in the soil, `--orphan-clump` 22 on every leaf cluster carried by its twig, `--drop-acorns` 23 on the hanging acorns on their stalks, `--float-cover` 24 on the ground cover joined to the soil, while the envelope holds.
+[`broadleaf-oak`](showcase/broadleaf-oak/) — the eighth `nature` piece: procedural mature, open-grown English oak on a grassy mound (a massive, short trunk with broad flutes and deep-furrowed bark plates flaring through seven buttresses into surface roots bedded in the soil, a low fork into five zig-zag scaffold limbs, the low ones reaching out sideways nearly level, that divide three more times into 155 tapered branches, each seated in its parent and narrowing past every junction by its child's area, a domed crown of 295 leaf-mass cushions — a hidden core on each carrier, 2075 faceted leaf clusters centred in the cores and shaded as billows by custom normals, 618 small lobed oak leaves on the outer clusters — dead twigs, acorns with scaly cups and glossy nuts hanging on stalks and lying in the grass among leaf litter, forked twigs and tufts), whose branch seats, da Vinci taper, nuts seated in their cups, plumb trunk and balanced crown, foot and roots sealed in the soil, cushions on their carriers, clusters in their cores and leaves in their clusters, acorns hung on their stalks and ground cover joined to the soil are recomputed from the mesh, through the same pipeline. `--float-branches` exits 17 on every branch seated in its parent, `--pop-nuts` 18 on every nut seated in its cup, `--lean-crown` 19 on plumb and balance, `--fat-twigs` 20 on the taper and area rule, `--perch-trunk` and `--arch-roots` 21 on the trunk and roots sealed in the soil, `--orphan-clump`, `--scatter-clusters` and `--shed-leaves` 22 on every cushion on its carrier, cluster in its core and leaf in its cluster, `--drop-acorns` 23 on the hanging acorns on their stalks, `--float-cover` 24 on the ground cover joined to the soil, while the envelope holds.
 
 [`farm-tractor`](showcase/farm-tractor/) — the ninth `vehicles` piece: procedural mid-century utility tractor standing in the ruts of a muddy farmyard with a puddle between its wheels (a cast-iron backbone of engine, bell housing, gearbox and rear axle housing with trumpets; a front axle oscillating on a pivot pin through the front support's lugs and two bushings, kingpins, spindles and a tie rod; 1.240 m rear tyres with 44 chevron bars rooted in the carcass and handed for forward travel, on dished rims with welded clamp lugs and cast-iron half-moon weights; ribbed front tyres; a grille shell with radiator and headlamps, a louvred bonnet, fuel tank and dash; a vertical exhaust stack with a hinged rain cap and an oil-bath pre-cleaner bowl; a raked steering column, a pan seat on a leaf spring, pedals and footplates; mudguards with a tail lamp and a work lamp; a three-point linkage with lift arms, lift rods, lower links, a stowed top link and the drawbar, and a PTO stub under its shield; paint chipped to primer at its edges, rust-streaked, sun-faded and mud-splashed). Asserts 122272 tris, twelve materials with face floors, zero coplanar cross-shell pairs, every tyre sunk 18–45 mm into the mud, hubs and the pivot pin coaxial, 14 link eyes on their pins, beads seated, 88 bars rooted and evenly pitched with their apex leading, body and wheels mirrored, wheelbase, tracks and rear-tyre diameter at their stated size, the mass centre inside the support triangle of the rear contacts and the front pivot by a quarter of the track, and one connected assembly; `--float-tyre` exits 16, `--cock-hub`, `--cant-pin` and `--unpin-link` 17, `--sink-tyre` and `--float-lugs` 18, `--skew-wheel`, `--wide-track`, `--tall-lugs` and `--odd-fender` 19, `--bunch-lugs` 20, `--reverse-lugs` 21, `--offset-pivot` 22, `--loose-lamp` 23, while the envelope holds.