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>

app/modules/billing/services/usage_service.py

@@ -92,7 +92,9 @@ class UsageService:
         self, db: Session, store_id: int
     ) -> MerchantSubscription | None:
         """Resolve store_id to MerchantSubscription."""
-        from app.modules.billing.services.subscription_service import subscription_service
+        from app.modules.billing.services.subscription_service import (
+            subscription_service,
+        )
         return subscription_service.get_subscription_for_store(db, store_id)
 
     def get_store_usage(self, db: Session, store_id: int) -> UsageData: