fix(ci): add explicit instruction to post review as PR comment

The AI reviewer was completing the review but not posting it because
the prompt didn't explicitly instruct it to use gh pr comment.

.github/workflows/ai-review.yml

@@ -127,6 +127,13 @@ jobs:
             End your review with:
             > 🤖 Reviewed by `${{ env.REVIEW_MODEL }}`
 
+            ## IMPORTANT: Posting the Review
+            After completing your analysis, you MUST post the review as a PR comment using:
+            ```
+            gh pr comment ${{ github.event.pull_request.number || github.event.issue.number || github.event.inputs.pr_number }} --body "<your review>"
+            ```
+            Use a heredoc for the body to handle multi-line content properly.
+
           claude_args: |
             --model ${{ env.REVIEW_MODEL }}
             --allowedTools "Bash(gh pr comment:*),Bash(gh pr diff:*),Bash(gh pr view:*),Read,Glob,Grep"