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/models/user.py

@@ -21,6 +21,7 @@ class User(Base):
     full_name = Column(String, nullable=True)
     nickname = Column(String, nullable=True)
     mobile_phone = Column(String, nullable=True)
+    note = Column(String, nullable=True)
     avatar_url = Column(String, nullable=True)
     created_at = Column(DateTime(timezone=True), default=_utcnow)