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/schemas/order.py

@@ -3,11 +3,18 @@ from datetime import datetime
 from typing import Optional, List
 
 
+class SelectedOptionInput(BaseModel):
+    id: Optional[int] = None
+    name: Optional[str] = None
+    price_delta: Optional[float] = None
+    extra_cost: Optional[float] = None
+
+
 class OrderItemInput(BaseModel):
     product_id: int
     quantity: int
-    selected_options: Optional[List[int]] = None
-    removed_ingredients: Optional[List[int]] = None
+    selected_options: Optional[List[SelectedOptionInput]] = None
+    removed_ingredients: Optional[List[str]] = None
     notes: Optional[str] = None