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>

core/dashboard/auth.py

@@ -20,6 +20,7 @@ logger = logging.getLogger(__name__)
 # Singleton instance
 _dashboard_auth: Optional["DashboardAuth"] = None
 
+
 @dataclass
 class DashboardSession:
     """Dashboard session information."""
@@ -30,6 +31,7 @@ class DashboardSession:
     user_type: str  # "master" or "api_key"
     key_id: str | None = None  # For API key sessions
 
+
 class DashboardAuth:
     """
     Dashboard authentication manager.
@@ -270,6 +272,7 @@ class DashboardAuth:
             )
         return None
 
+
 def get_dashboard_auth() -> DashboardAuth:
     """Get or create the singleton DashboardAuth instance."""
     global _dashboard_auth