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/schemas/printer.py

@@ -11,6 +11,7 @@ class PrinterBase(BaseModel):
     port: int = 9100
     is_active: bool = True
     protocol: str = "escpos_tcp"
+    line_width: int = 48
 
 
 class PrinterCreate(PrinterBase):
@@ -23,6 +24,7 @@ class PrinterUpdate(BaseModel):
     port: Optional[int] = None
     is_active: Optional[bool] = None
     protocol: Optional[str] = None
+    line_width: Optional[int] = None
 
 
 class PrinterOut(PrinterBase):