ci: fix codex-action pin comment format to satisfy workflow contract test

[igerber]

Summary

• Fix the # v1.11 pin comment format introduced in ci: pin openai/codex-action back to v1.11 (v1.12 hangs after turn completes) #797: TestWorkflowCodexActionContract::test_run_codex_uses_pinned_action anchors the version comment to end-of-line (openai/codex-action@<sha> # v1[.N]$), and the trailing rationale prose on the uses: line broke it on main (Rust Backend Tests, pure Python leg: 1 failed, 13053 passed). The rationale now lives on its own comment lines above the pin; the uses: line ends with # v1.11.
• No functional change: the pin stays at v1.11 (52fe01ec).

Methodology references (required if estimator / math changes)

• Method name(s): N/A - no methodology changes
• Paper / source link(s): N/A
• Any intentional deviations from the source (and why): None

Validation

• Tests added/updated: No test changes; tests/test_openai_review.py now passes locally (264 passed), including the previously failing contract test.
• Backtest / simulation / notebook evidence (if applicable): N/A

Security / privacy

• Confirm no secrets/PII in this PR: Yes

[github-actions]

Overall Assessment: ✅ Looks good

Executive Summary

• The change is limited to a GitHub Actions comment format.
• The action remains pinned to the same immutable SHA and version.
• No methodology, estimator, inference, runtime, or security behavior changes.
• The revised uses: line satisfies the described end-of-line contract.

Methodology

No findings. The Methodology Registry is not implicated because no statistical code or defaults changed.

Code Quality

No findings. Moving the rationale above the uses: line preserves clarity and valid YAML structure.

Performance

No findings. No runtime behavior changed.

Maintainability

No findings. The pin rationale remains adjacent to the dependency.

Tech Debt

No findings. The existing re-bump condition remains documented.

Security

No findings. The action remains pinned to the same full commit SHA.

Documentation/Tests

No findings. The modification directly restores compatibility with the existing workflow contract test; additional tests are unnecessary for this comment-only change.