feat(local_backend): reservations, print analytics, workday summary, zone-PIN management

- New reservations module: model, schema, router (CRUD + status updates + upcoming alerts)
  and background task for auto-expiring stale reservations
- Reports: print_products, print_categories, print_tables analytics endpoints
  plus meta_products and business_day_summary for workday close/view flow
- printer_service: configurable font sizes/weights, donut/bar chart print layout helpers,
  analytics print blocks per printer
- tables/schemas: surfaced color, zone, and other new fields on Table, Product, User, Printer
- demo_seed.py for quick dev DB population; wipe_database.py utility

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

local_backend/routers/waiters.py

@@ -52,10 +52,14 @@ def create_waiter(body: UserCreate, db: Session = Depends(get_db), user: User =
         full_name=body.full_name,
         nickname=body.nickname,
         mobile_phone=body.mobile_phone,
+        email=body.email,
+        note=body.note,
     )
     db.add(new_user)
     db.commit()
     db.refresh(new_user)
+    db.add(WaiterZone(waiter_id=new_user.id, group_id=None))
+    db.commit()
     return new_user