Add merging documentation to review-pr command

- Document tea pulls merge as the correct merge method
- Add warning against using Gitea API with admin credentials
- Document tea comment as alternative to interactive tea pulls review

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

commands/review-pr.md

@@ -20,3 +20,19 @@ Ask the user what action to take:
 - **Merge**: Post review summary as comment, then merge with rebase style
 - **Request changes**: Leave feedback without merging
 - **Comment only**: Add a comment for discussion
+
+## Merging
+
+Always use tea CLI for merges to preserve user attribution:
+
+```bash
+tea pulls merge <number> --style rebase
+```
+
+For review comments, use `tea comment` since `tea pulls review` is interactive-only:
+
+```bash
+tea comment <number> "<review summary>"
+```
+
+> **Warning**: Never use the Gitea API with admin credentials for user-facing operations like merging. This causes the merge to be attributed to the admin account instead of the user.