fix(ci): fix black/ruff failures, add CoC and PR template

- Fix Python formatting (sync no longer strips blank lines from .py files)
- Remove test_community_build.py (tests private sync module)
- Fix ruff warnings in test files
- Add CODE_OF_CONDUCT.md
- Add .github/PULL_REQUEST_TEMPLATE.md

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

plugins/gitea/client.py

@@ -11,6 +11,7 @@ from typing import Any
 
 import aiohttp
 
+
 class GiteaClient:
     """
     Gitea REST API client for HTTP communication.