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>

CODE_OF_CONDUCT.md

@@ -0,0 +1,40 @@
+# Code of Conduct
+
+## Our Pledge
+
+We as members, contributors, and leaders pledge to make participation in our
+community a welcoming experience for everyone, regardless of background or
+identity.
+
+## Our Standards
+
+Examples of behavior that contributes to a positive environment:
+
+- Using welcoming and inclusive language
+- Being respectful of differing viewpoints and experiences
+- Gracefully accepting constructive criticism
+- Focusing on what is best for the community
+- Showing empathy towards other community members
+
+Examples of unacceptable behavior:
+
+- Trolling, insulting or derogatory comments, and personal attacks
+- Public or private unwelcome conduct
+- Publishing others' private information without explicit permission
+- Other conduct which could reasonably be considered inappropriate
+
+## Enforcement
+
+Instances of unacceptable behavior may be reported to the project maintainers
+at **contact@mcphub.dev**. All complaints will be reviewed and investigated
+promptly and fairly.
+
+Project maintainers who do not follow or enforce this Code of Conduct may face
+temporary or permanent repercussions as determined by other members of the
+project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant](https://www.contributor-covenant.org/),
+version 2.1, available at
+[https://www.contributor-covenant.org/version/2/1/code_of_conduct/](https://www.contributor-covenant.org/version/2/1/code_of_conduct/).