fix(examples): redesign export-preset-axis as a banded radio mast with measured axis gizmos

The review judged the hero weak: dim olive-on-grey, a thin undesigned pole
with a box, and the Godot copy lying sideways read as "fell over" rather
than as an axis convention.

- The source is now a modelled radio mast: stepped chamfered concrete
  footing, bolted flange, tapered mast in red/white aviation bands with
  steel collars, three sector panels, a shrouded microwave dish on a raked
  arm, an equipment cabinet, and a red obstruction lamp under a lightning
  rod whose point is the witnessed tip vertex. Eight materials.
- Each re-import gets a modelled X/Y/Z gizmo. The frame is measured, not
  placed: the render path picks the axis-aligned rotation mapping source
  vertices onto the re-import (fit_err printed; exit 12 above 1 mm). Unity
  shows blue Z up; Godot shows green Y up and blue Z along the lying mast.
- The camera looks along +X so the lying mast shows its full length.
- The render path now runs gallery_asset_quality (exit 11).

The check contract is unchanged; the same checks pass on 4.5.11, 5.1.2
and 5.2.1, and --same-axis still exits 9.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>

Author: TMHSDigital

README.md

@@ -850,13 +850,13 @@ byte-identical on 4.5.11 and 5.1.2 and guarded against future renames.
 </tr>
 <tr>
 <td width="46%" valign="middle">
-<a href="examples/export-preset-axis/"><img src="examples/export-preset-axis/preview.webp" alt="Export preset axis: a radio beacon exported under Unity and Godot glTF presets and re-imported side by side on a dark studio floor - Unity standing with a glowing cap, Godot lying on its base - proving the two files have different vertex orientation" /></a>
+<a href="examples/export-preset-axis/"><img src="examples/export-preset-axis/preview.webp" alt="Export preset axis: a red-and-white radio mast exported under Unity and Godot glTF presets and re-imported side by side on a dark studio floor, each beside a red-green-blue axis gizmo - Unity standing with blue Z up, Godot lying with green Y up and blue Z along the mast - proving the two files have different vertex orientation" /></a>
 </td>
 <td valign="middle">
 
 ### [export-preset-axis](examples/export-preset-axis/)
 
-The same beacon mesh under the Unity (`export_yup=True`) and Godot
+The same radio-mast mesh under the Unity (`export_yup=True`) and Godot
 (`export_yup=False`) glTF presets. Re-importing each file proves the axis
 conversion: Unity stands, Godot lies along `-Y`. `--same-axis` exports both
 Y-up and the differ check exits 9. Neighbor of

docs/gallery/asset-sheets/export-preset-axis.webp

@@ -618,11 +618,11 @@ <h2><a href="gltf-export-roundtrip/">gltf-export-roundtrip</a></h2>
       </article>
       <article class="card" data-tags="export">
         <a class="card-media" href="export-preset-axis/" tabindex="-1" aria-hidden="true">
-          <img src="assets/export-preset-axis-hero.webp" alt="Two copies of a lamp-post beacon: the left one standing upright, the right one lying on its side." loading="lazy" decoding="async" />
+          <img src="assets/export-preset-axis-hero.webp" alt="Two re-imports of a red-and-white radio mast with axis gizmos: the Unity copy stands with blue Z up, the Godot copy lies on the floor with green Y up and blue Z along the mast." loading="lazy" decoding="async" />
         </a>
         <div class="card-body">
           <h2><a href="export-preset-axis/">export-preset-axis</a></h2>
-          <p class="teaches">A radio beacon exported under Unity and Godot glTF presets and re-imported, proving the two files have different vertex orientation</p>
+          <p class="teaches">A radio mast exported under Unity and Godot glTF presets and re-imported, proving the two files have different vertex orientation</p>
           <p class="witnesses"><span class="tag">witnesses</span> Unity export_yup=True round-trips standing (x,y,z); Godot export_yup=False reimports lying along -Y as (x,-z,y); --same-axis exits 9; exporter RNA is guarded so a future kwarg rename fails loudly</p>
           <a class="card-link" href="export-preset-axis/">View example<span class="sr-only"> export-preset-axis</span> <span aria-hidden="true">&rarr;</span></a>
         </div>

docs/gallery/assets/export-preset-axis-hero.webp

@@ -1,6 +1,6 @@
 # Export Preset Axis
 
-A runnable example that exports the same radio-beacon mesh under the Unity
+A runnable example that exports the same radio-mast mesh under the Unity
 and Godot glTF presets from
 [`engine-export-presets`](../../skills/engine-export-presets/SKILL.md) and
 re-imports both files. The check is on coordinates, not a screenshot: Unity
@@ -26,8 +26,25 @@ vs Z-up on disk for one file) and [`unapplied-scale-gltf`](../unapplied-scale-gl
 (`export_apply` is modifiers, not object scale). This example names the
 Unity vs Godot presets and asserts the re-imported orientations diverge.
 
-The still stages the two reimports side by side: standing Unity left, lying
-Godot right. If `export_yup` were the same on both, the pair would match.
+The subject is a radio mast chosen because "up" is unmistakable on it: a
+stepped concrete footing, a bolted base flange, a tapered mast in red and
+white aviation bands with steel collars, three sector panel antennas, a
+shrouded microwave dish on a raked arm, an equipment cabinet, and a red
+obstruction lamp under a lightning rod. The rod's point is the witnessed tip
+vertex.
+
+The still stages the two re-imports side by side: the Unity copy standing on
+the left, the Godot copy lying along the floor on the right. Beside each sits
+a modelled X/Y/Z axis gizmo (red, green, blue) showing that re-import's
+frame. The gizmo is measured, not placed: the render path tries all 24
+axis-aligned rotations and keeps the one that maps the source vertices onto
+the re-imported vertices (worst nearest-vertex distance, printed as
+`fit_err`; exit 12 if it exceeds 1 mm). The Unity gizmo comes out as the
+identity, blue Z up. The Godot gizmo comes out as `Y -> +Z, Z -> -Y`: green
+Y points up and blue Z runs along the lying mast. The mast didn't fall over.
+The Godot file stores Z-up coordinates, and the importer reads them as
+Y-up. If `export_yup` were the same on both, the two copies and both gizmos
+would match.
 
 ## Run
 
@@ -39,14 +56,15 @@ blender --background --python export_preset_axis.py --
 blender --background --python export_preset_axis.py -- --same-axis
 
 # Also render a still (EEVEE on a GPU host; use --engine cycles on GPU-less hosts):
-blender --background --python export_preset_axis.py -- --output beacon.png
-blender --background --python export_preset_axis.py -- --output beacon.png --engine cycles
+blender --background --python export_preset_axis.py -- --output mast.png
+blender --background --python export_preset_axis.py -- --output mast.png --engine cycles
 ```
 
 ## Exit codes
 
 Per-script sequential checks. `9` is a valid check code; there is no rule
-against it. `10` is the shared framing helper.
+against it. `10` is the shared framing helper and `11` on the render path is
+the shared asset-quality helper.
 
 | Code | Meaning |
 | --- | --- |
@@ -61,7 +79,8 @@ against it. `10` is the shared framing helper.
 | 8 | Godot reimport is not lying along Y, or reimported tip mismatch |
 | 9 | Reimported orientations did not differ (`--same-axis` lands here) |
 | 10 | Gallery framing violation |
-| 11 | `--same-axis` did not collapse the axis difference |
+| 11 | `--same-axis` did not collapse the axis difference; also asset-quality floor violation (render path) |
+| 12 | Render path: no axis-aligned rotation maps the source onto a re-import, so the gizmo frame could not be measured |
 
 The `blender-smoke` workflow runs the check on Blender 5.2 LTS and 4.5 LTS
 (5.1 on the weekly cron, the `needs-5.1` PR label, or manual dispatch).