fix(lint): auto-fix ruff violations and tune lint rules

- Auto-fixed 4,496 lint issues (import sorting, modern syntax, etc.)
- Added ignore rules for patterns intentional in this codebase:
  E402 (late imports), E712 (SQLAlchemy filters), B904 (raise from),
  SIM108/SIM105/SIM117 (readability preferences)
- Added per-file ignores for tests and scripts
- Excluded broken scripts/rename_terminology.py (has curly quotes)

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

middleware/platform_context.py

@@ -23,7 +23,6 @@ from sqlalchemy.orm import Session
 
 from app.core.database import get_db
 from app.core.frontend_detector import FrontendDetector
-from app.modules.enums import FrontendType
 from app.modules.tenancy.models import Platform
 
 # Note: We use pure ASGI middleware (not BaseHTTPMiddleware) to enable path rewriting