Revise shell policy reduction gate

[Aaronontheweb]

Summary

• record the final direct-evaluator footprint and safe reduction boundary
• require reduction against the post-corpus checkpoint and frozen control-flow baseline
• preserve tested security distinctions and the compatibility removal path
• record API, persistence, coverage, CRAP, native, and CI evidence

Validation

• OpenSpec strict validation passed for both active changes
• copyright header verification passed
• diff checks passed
• PR Collapse shell policy phase machinery #1965 passed Ubuntu, macOS, Windows, and native smoke gates
• full local Actors and Security suites passed on the merged implementation