fix: forward governed context in v2 decision admission

[Brad-Edwards]

Summary

Forward authenticated caller identity and crossing evidence from the public v2 decision-surface selection API into ordinary governed action admission. Selection remains bound to the delivered exact-cut surface, while existing crossing policy decides whether the caller and evidence authorize ingress.

Requirement UIDs

• (none — bug/refactor/maintenance run; see Traceability section below)

Related Issues

Closes #1357

ADR Impact

• ADR-095

Changes

• Parse v2 selection submission options through the shared participant submission contract and forward identity and crossing evidence to governed admission.
• Record actor and bounded request context for early selection rejections.
• Cover valid and rejected governed selections and document the v2 invocation.
• Refresh specification coverage and formal semantic validation evidence releases for the current source digest.

Test Plan

• Unit tests pass
• Integration tests pass if applicable
• Full completion suite required in CI before merge
• No coverage regression

Targeted v2 runtime tests: 17 passed. Specification coverage checker and tests, formal semantic validation checker and tests, versioned evidence tests, and targeted fast feedback passed locally. Hosted CI and SonarCloud will validate the published revision.

Ground Control Checks

• Repository policy checks required in CI before merge
• Pre-push Codex review completed; all findings fixed or dispositioned

Traceability

• IMPLEMENTS: Forward governed invocation context through v2 decision admission #1357
• TESTS: implementations/python/tests/test_sem_220_participant_decision_surface_v2_runtime.py, implementations/python/tests/test_specification_coverage.py, implementations/python/tests/test_formal_semantic_validation.py, implementations/python/tests/test_issue_989_versioned_evidence.py

Checklist

• Code follows the project's coding standards
• Changelog: owned by Release Please (generated from the Conventional Commit PR title; no per-PR fragment)
• Architectural docs updated if stack, package structure, or key behaviors changed

Documentation

Updated: see diff.

[Brad-Edwards]

Ground Control delivery — this pull request delivers issue #1357; Phase E runs on merge.