ci: require admin approval for large PR reviews

[idy]

Closes #47

Summary

• Keep the shared 100,000,000-byte total diff ceiling, but automatically review only complete diffs up to 5,000,000 bytes.
• For a larger diff, require an unquoted @codex review approve <current full head SHA> PR comment from a user with admin permission in the calling repository. Permission lookup and head matching happen in the trusted reusable workflow; failed lookups deny approval.
• Reject unapproved large diffs before Codex bootstrap. Preserve existing caller events and inputs; no Environment or per-repository reviewer configuration is required.
• Expand diff read buffers to accommodate the existing 100 MB approved ceiling, and document the admin command.

Validation

• node .github/scripts/review-request/test.mjs
• node .github/scripts/pr-review/test.mjs
• node .github/scripts/pr-readiness/test.mjs
• node .github/scripts/issue-review/test.mjs
• actionlint -ignore 'property "workflow_(repository|sha)" is not defined' .github/workflows/*.yml
• git diff --check

[github-actions]

✅ OpenAI PR Review: PASS

Conclusion: Ready from the OpenAI review perspective. PR format, linked Issue design, and code/plan conformance passed with no actionable findings.

Review checks

Check	Result
PR format	✅ PASS
Issue design	✅ PASS
Code & plan conformance	✅ PASS

Scope: 9689093ad0 · ac4d5d7411..9689093ad0 · full · 1 diff chunk

Usage: 1m 14s · 439,679 tokens · 86.1% cache hit · credits unavailable

Summary

The complete diff review found no actionable code findings or Issue-plan-conformance blockers.

Review metadata

• Commit: 9689093ad0
• Range: ac4d5d7411..9689093ad0
• Mode: full
• Diff chunks: 1
• Model: gpt-6-sol
• Reasoning effort: low
• Session: repo-1309321116-pr-48-v2
• Generation: 4e417b4f21095454e71445573a19610b4a71ce9c7f21b569ea3942ce2661825d
• Evidence: da1b6d97136bb29893fbe60018e8422217ba52e41098f6cd8c629699ba2b2d37

Totals

• Input: 436,472
• Cached input: 375,592
• Cache write: 59,724
• Output: 3,207
• Reasoning: 712
• Total: 439,679
• Estimated credits: unavailable for this model

Token and cache details

Stage	Mode	Target	Time	Input	Cached	Hit	Output	Total	Credits
pr	deterministic	format rules	0s	0	0	0.0%	0	0	N/A
pr	full	pr	13s	57,747	42,272	73.2%	572	58,319	N/A
issue	full	Issue #47	14s	54,287	49,024	90.3%	537	54,824	N/A
code	full	chunk 1/1	32s	170,814	135,257	79.2%	1,574	172,388	N/A
code	full	aggregate	15s	153,624	149,039	97.0%	524	154,148	N/A