fix: let /review satisfy ship readiness

[malikrohail]

Summary

• add a final /review readiness log entry for the main review result
• teach /ship to treat review and plan-eng-review as valid Eng Review sources
• keep the fix scoped to same-branch /review -> /ship handoff only
• add generator and validation coverage for the new readiness contract

Scope

This is the narrow slice of #280:

• fixed: same-branch /review -> /ship readiness handoff
• not fixed: cross-branch review log isolation
• not fixed: CEO plan discovery in /plan-eng-review
• not fixed: office-hours branch-based file naming

Problem

On current main, /review never persists a top-level review readiness entry, and /ship only treats plan-eng-review as satisfying the Eng Review gate. That leaves the Review Readiness Dashboard in a false NOT CLEARED state even after a real /review run.

Fix

• add Step 5.8: Persist Eng Review result to /review
• log a top-level {"skill":"review", ...} entry after a real review completes
• update the ship-specific readiness dashboard text so Eng Review accepts either review or plan-eng-review
• update the missing-gate prompt so it tells the user to run /review or /plan-eng-review

Refs #280.

Verification

• bun run gen:skill-docs
• bun run gen:skill-docs --host codex
• bun test test/gen-skill-docs.test.ts test/skill-validation.test.ts
• bun test
• helper smoke with isolated state dir:
  • write a {"skill":"review"} entry via bin/gstack-review-log
  • confirm bin/gstack-review-read returns it

[malikrohail]

@garrytan verified on March 22, 2026.

I kept this PR intentionally narrow to the /review -> /ship handoff:

• no cross-branch review-log redesign
• no CEO plan discovery changes
• no office-hours file-naming changes

It only makes a normal /review run satisfy the existing Eng Review gate on the same branch, with generator + validation coverage and a branch-local helper smoke check behind the PR body.