feat(governance): trust exact-head Validator App reviews

[tom-sapletta-com]

Summary

• add an exact allowlist for the independent Validator GitHub App
• accept human or allowlisted App approval only on the current head SHA
• reject unknown bots, stale/dismissed reviews, self-review, and malformed policy
• add deterministic approval fixtures to the governance gate

Validation

• make governance
• npm run verify
• make smoke
• make examples-check
• make docker-smoke
• gold v1/v2: 100%
• full Docker E2E: 342/342 with JDK 17

Ticket: ticket-018, AC-30..AC-40. AC-40 intentionally remains open until this bootstrap policy is independently reviewed/merged and the real Validator App reviews PR #13.

[ifuri-validator-agent]

Deterministic Validator approval for exact head 17715cc6af4d983918462a23d0f37a810b910eec.

Ticket: ticket-018
Correlation ID: todo2code-pr-14-ticket-018-17715cc6
Model: openrouter/z-ai/glm-5.2
Advisory LLM verdict: APPROVE
Advisory summary: The visible diff consists of ticket-018 documentation updates (README, ai-codex logs, changelog) describing planning, implementation notes, and acceptance criteria for a Validator App allowlist and direct-PR strategy. The content is narrative/markdown only; no executable source, workflow, or governance logic changes are visible in the provided diff. Security-relevant claims (scoped App tokens, exact-head binding, fail-closed checks, no secrets in logs, advisory-only LLM verdicts) are consistent with defensive design, though they describe intended behavior rather than code in this diff.
Advisory findings: none
The LLM output above is advisory and was not used as the approval trust root.
Merge was not requested or performed.