Pin action authority mode and grant claim requirements

[aruintelligence]

Change

• Persist the file authority's configured mode and reject workers that issue, revoke, or dispatch with a different mode, including checkpoint plus claim configurations.
• Mark externally anchored grants with their required claim protocol and block dispatch if the worker lacks it.
• Fail closed when an existing store loses its mode record; recheck after awaited external claims and epoch advances.
• Cover cross-process downgrades, missing records, and the checkpoint protocol 2 interaction. Document the explicit reconciliation and migration boundary.

Verification

• npm test — 1,011 passed
• node scripts/check-package-artifact.mjs — 42 checks passed
• npm run compatibility:consumer — passed
• npm run check:links — 411 Markdown files passed

Scope

This is the one-machine file authority pilot. The local mode record does not bind a particular external backend or protect against same-identity store tampering. Existing stores without the mode record require operator reconciliation and migration; they do not silently adopt a mode.