ci: fix codex-action pin comment format to satisfy workflow contract test (#798)

Author: igerber

.github/workflows/ai_pr_review.yml

@@ -515,7 +515,9 @@ jobs:
       - name: Run Codex
         id: run_codex
         if: steps.pr.outputs.is_fork == 'false'
-        uses: openai/codex-action@52fe01ec70a42f454c9d2ebd47598f9fd6893d56 # v1.11 — pinned: v1.12 hangs after turn completes (openai/codex-action#150); re-bump once #151 ships
+        # Pinned to v1.11: v1.12 hangs after the turn completes
+        # (openai/codex-action#150); re-bump once #151 ships.
+        uses: openai/codex-action@52fe01ec70a42f454c9d2ebd47598f9fd6893d56 # v1.11
         with:
           openai-api-key: ${{ secrets.OPENAI_API_KEY }}
           prompt-file: .github/codex/prompts/pr_review_compiled.md