Fix: eagerload series.sets i admin og API (MissingGreenlet i async mode)

backend/app/main.py

@@ -6,6 +6,7 @@ from fastapi.templating import Jinja2Templates
 from contextlib import asynccontextmanager
 from sqlalchemy import select
 
+from pathlib import Path
 from .database import engine, async_session, Base
 from .routers import auth, admin, cards
 from .auth import get_current_user, hash_password
@@ -27,6 +28,9 @@ async def lifespan(_app: FastAPI):
                 role="admin",
             ))
             await session.commit()
+
+    # Ensure image upload directory exists
+    Path("app/static/images").mkdir(parents=True, exist_ok=True)
     yield