Fix ruff lint errors across codebase

- Auto-fix F401 (unused imports) and I001 (unsorted imports) with ruff --fix
- Manually fix E501 (line too long) in alembic migrations and src/ models
- Run ruff format to ensure consistent formatting

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/cartsnitch_api/main.py

@@ -6,10 +6,10 @@ from fastapi import APIRouter, FastAPI
 
 from cartsnitch_api.auth.routes import router as auth_router
 from cartsnitch_api.cache import cache_client
+from cartsnitch_api.middleware.audit import add_audit_middleware
 from cartsnitch_api.middleware.cors import add_cors_middleware
 from cartsnitch_api.middleware.error_handler import add_error_handlers, add_error_monitor_middleware
 from cartsnitch_api.middleware.rate_limit import add_rate_limit_middleware
-from cartsnitch_api.middleware.audit import add_audit_middleware
 from cartsnitch_api.routes.alerts import router as alerts_router
 from cartsnitch_api.routes.coupons import router as coupons_router
 from cartsnitch_api.routes.health import router as health_router
@@ -26,6 +26,7 @@ from cartsnitch_api.routes.user import router as user_router
 @asynccontextmanager
 async def lifespan(app: FastAPI):
     from cartsnitch_api.database import dispose_engine
+
     await cache_client.initialize()
     yield
     await cache_client.close()