chore: clean legacy setup artifacts

backend/app/main.py

@@ -40,9 +40,6 @@ async def lifespan(_: FastAPI):
     aggregator_task = asyncio.create_task(run_hourly_metric_aggregation(stop_event))
     await start_log_writer()
     await start_security_log_writer()
-    # Ensure models are imported so metadata is populated
-    from app.models import user as user_model  # noqa: F401
-
     if settings.ENV == "development":
         async with engine.begin() as conn:
             await _ensure_legacy_primary_keys(conn)