Fix offline sync priority, idempotent check state, and add loading spinner for meal plan import

app/main.py

@@ -47,6 +47,7 @@ from .database import (
     add_shopping_item,
     add_shopping_items_bulk,
     toggle_shopping_item,
+    set_shopping_item_checked,
     delete_shopping_item,
     delete_checked_shopping_items,
     clear_shopping_list,
@@ -1075,8 +1076,11 @@ async def api_add_shopping_bulk(payload: ShoppingBulkCreate):
 
 
 @app.post("/api/shopping-list/{item_id}/toggle")
-async def api_toggle_shopping_item(item_id: int):
-    updated = toggle_shopping_item(item_id)
+async def api_toggle_shopping_item(item_id: int, checked: Optional[bool] = Query(None)):
+    if checked is not None:
+        updated = set_shopping_item_checked(item_id, checked)
+    else:
+        updated = toggle_shopping_item(item_id)
     if not updated:
         raise HTTPException(status_code=404, detail="Eintrag nicht gefunden.")
     await shopping_ws_manager.broadcast({"action": "items_updated", "items": get_shopping_list()})