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/system.py

@@ -129,7 +129,7 @@ def test_order_print(printer_id: int, db: Session = Depends(get_db), user: User
     printer = db.query(Printer).filter(Printer.id == printer_id).first()
     if not printer:
         raise HTTPException(status_code=404, detail="Printer not found")
-    success, error = printer_service.send_test_order_print(printer.ip_address, printer.port, db)
+    success, error = printer_service.send_test_order_print(printer.ip_address, printer.port, db, printer.line_width)
     return {"success": success, "error": error}