feat: initial commit — local services (backend + manager dashboard + waiter PWA)

Includes all work to date:
- local_backend: FastAPI backend with products, orders, tables, shifts, cloud sync
- manager_dashboard: React manager UI with product/category management, reports, settings
- waiter_pwa: React PWA for waiter devices
- Category reparent endpoint and UI
- Waiter domain: local_ip sent on heartbeat, waiter_domain persisted from cloud response
- QR code modal in AppInfoTab for waiter domain
- Product form: number input spinners removed, category pre-selected on new product
- Category row: count badge moved to far right

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

local_backend/models/printer.py

@@ -0,0 +1,17 @@
+from sqlalchemy import Column, Integer, String, Boolean
+from sqlalchemy.orm import relationship
+from database import Base
+
+
+class Printer(Base):
+    __tablename__ = "printers"
+
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String, nullable=False)
+    ip_address = Column(String, nullable=False)
+    port = Column(Integer, default=9100, nullable=False)
+    is_active = Column(Boolean, default=True, nullable=False)
+    protocol = Column(String, default="escpos_tcp", nullable=False)
+
+    products = relationship("Product", back_populates="printer_zone")
+    print_logs = relationship("PrintLog", back_populates="printer")