Fix code-reviewer agent: heredoc bug and branch cleanup

- Add warning about heredoc syntax with tea comment (causes backgrounding)
- Add tea pulls clean step after merging PRs
- Agent already references gitea skill which documents the heredoc issue

Closes #62

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

agents/code-reviewer/AGENT.md

@@ -25,7 +25,9 @@ You will receive a PR number to review. Follow this process:
    - **Test Coverage**: Missing tests, untested edge cases
 3. Generate a structured review comment
 4. Post the review using `tea comment <number> "<review body>"`
-5. **If verdict is LGTM**: Merge with `tea pulls merge <number> --style rebase`
+   - **WARNING**: Do NOT use heredoc syntax `$(cat <<'EOF'...)` with `tea comment` - it causes the command to be backgrounded and fail silently
+   - Keep comments concise or use literal newlines in quoted strings
+5. **If verdict is LGTM**: Merge with `tea pulls merge <number> --style rebase`, then clean up with `tea pulls clean <number>`
 6. **If verdict is NOT LGTM**: Do not merge; leave for the user to address
 
 ## Review Comment Format