fix: align worker intent, recovery, and delivery contracts

[SamSherpaDev]

Summary

• Preserve all accepted engineering requirements in private review intent while separating provenance, worker-control instructions, and concise public PR prose.
• Apply one shared completion contract to new briefs, existing-brief launches, and scout promotion: authorized validation starts after commit, and completion requires an exact-current-head green PR. Other delivery modes and merge authority remain unchanged.
• Allow one evidence-backed local precondition correction, clarify scoped decision authority, and replace redundant runtime inventory with safety rules and owner pointers.

Validation and limits

Local review, targeted stock Bash 3.2 tests, captured launch/promotion behavior, documentation checks, and pinned lint passed. Review also corrected legacy-brief delivery, explicit privacy exclusions, and source-only test assertions.

GitHub checks have not executed and await maintainer approval. This PR is not green or ready to merge. The changes do not repair the third-party publisher or rewrite runtime recovery; those remain separate follow-ups.

Pipeline verification

Updates from git push no-mistakes