Fix order saving, isMyOrder, blocked waiters, options pricing; add preferences, table groups, product images

Backend:
- OrderItemInput accepts option objects {id,name,price_delta} instead of int IDs
- extra_cost from selected options added to unit_price snapshot
- GET /api/products/?all=true for manager (includes unavailable)
- PUT /api/products/{id} now replaces options, ingredients, preference_sets
- POST /api/products/{id}/image — persistent image upload to /app/data/product_images
- New models: ProductPreferenceSet, ProductPreferenceChoice, TableGroup
- tables: group_id FK, hard delete (?hard=true), batch create POST /api/tables/batch
- GET /api/tables/groups + POST/PUT/DELETE groups endpoints
- POST /api/auth/me endpoint for token rehydration
- Auto-migration on startup for new columns

PWA:
- AuthRehydrator: fetches /auth/me on load so isMyOrder works after page reload
- 401 response force-logs out (covers blocked waiters)
- ItemOptionsModal: uses extra_cost correctly, shows preferences as radio buttons

Manager:
- ProductsPage: shows unavailable products greyed out, category color picker + reorder,
  full option/ingredient/preference editing, image upload
- TablesPage: table groups, auto-increment, deactivate vs hard delete, batch add

local_backend/routers/orders.py

@@ -109,13 +109,18 @@ def add_items(
         product = db.query(Product).filter(Product.id == item_in.product_id).first()
         if not product or not product.is_available:
             raise HTTPException(status_code=400, detail=f"Product {item_in.product_id} not available")
+        # Calculate extra cost from selected options
+        extra_cost = sum(
+            (o.price_delta or o.extra_cost or 0.0)
+            for o in (item_in.selected_options or [])
+        )
         item = OrderItem(
             order_id=order_id,
             product_id=item_in.product_id,
             added_by=user.id,
             quantity=item_in.quantity,
-            unit_price=product.base_price,  # price snapshot
-            selected_options=json.dumps(item_in.selected_options) if item_in.selected_options else None,
+            unit_price=product.base_price + extra_cost,  # price snapshot with options
+            selected_options=json.dumps([o.model_dump() for o in item_in.selected_options]) if item_in.selected_options else None,
             removed_ingredients=json.dumps(item_in.removed_ingredients) if item_in.removed_ingredients else None,
             notes=item_in.notes,
         )