Add Commander-governed native constraint core

[FreshSoftware4]

Purpose

Advance the execution-native Locus64 spine from two primitive operation classes to the first coherent constraint core, under an explicit Commander change chain.

Completed change chain

LOCUS64_CONSTRAINT_CORE_CHANGE_CHAIN.athens is closed with five evidence-gated links:

1. dimension algebra
2. context consistency
3. guarded obligation
4. native RNA/DNA surface
5. constraint-core closure

The parent LOCUS64_EXECUTION_COHERENCE_RAIL.athens has advanced:

native-constraint-core       complete
proof-producing-congruence   current
incremental-closure          next

Native capability added

• seven signed dimension axes packed into one u64
• quantity types over existing carrier types
• dimension-checked addition, multiplication, division, and square root
• compact constraint nodes using the existing node/port algebra
• persistent context deltas with contradiction rejection before mutation
• guarded square root with three lawful outcomes:
  • kernel witness when nonnegativity is proven
  • structured rejection when refuted
  • native obligation when unresolved
• decoder-side re-execution of operation, context, and evidence law
• canonical L64R1 -> L64D -> L64R1 -> L64D fixed points for discharged and unresolved guards

Burden control

No new registry, receipt family, solver object, string identity, JSON schema, or parallel authority graph was introduced. The public surface remains within the established caps:

• 10 public structs
• 7 public enums
• Node <= 32 bytes
• Port <= 8 bytes
• Dimension <= 8 bytes

Large implementation files were factored only at existing item boundaries to improve review locality without adding authority layers or changing canonical bytes.

Verification

Local isolated verification passed:

32 native tests
cargo fmt --all --check
cargo clippy -p l64-native --all-targets -- -D warnings

GitHub run 29990484222 passed on source head cbcbfe5d9c4f34baf0ca54306c77a85ac970bd26:

• formatting
• complete workspace tests
• strict native-core Clippy

The commits after that green source head modify only the two Commander rail files and CI event deduplication; no Rust or CLI source changed.

CI coordination repair

Commander branches now run the native gate on push; same-repository PR events skip the duplicate heavy job, while fork PRs retain pull-request coverage. Rail files are watched paths so governed state changes remain part of release identity.

Remaining rail

The next stage is proof-producing congruence: equivalence may not merge without checked provenance. It is followed by incremental closure, native upper projections, and final legacy authority quarantine.