feat(finish): enforce start receipt completion gates

[PatrickJS]

Summary

• enforce finish completion gates from the recorded start decision receipt
• record safe release-preflight and release-deferral evidence in the Auto Git ledger
• cover coordinated local-only, release-preflight, follow-up-thread, and local-review finish routes
• regenerate the auto-git gist package output

Verification

• pnpm run gists:package
• pnpm run gists:check
• pnpm run verify