chore(meta): document protected branches in CLAUDE.md

main, maintenance, server, client are protected on Gitea.
Agents must not delete or force-push to these branches.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -97,6 +97,7 @@ Key rules:
 - **All flags must be explicit** — omitting `--login` or `--repo` triggers interactive prompts that crash in Claude Code (no TTY)
 - **Use `--output simple`** for machine-readable output (no table borders)
 - **`tea pr reject` does not work on your own PRs** — use `tea comment` instead
+- **Never delete protected branches:** `main`, `maintenance`, `server`, `client` are protected on Gitea. Do not use `tea pr clean`, `git push --delete`, or `git branch -D` on these branches.
 
 ### File conventions
 - Decisions: domain files in `decisions/` (see `decisions/README.md` for index)