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/user.py

@@ -0,0 +1,70 @@
+from sqlalchemy import Column, Integer, String, Boolean, DateTime, ForeignKey
+from sqlalchemy.orm import relationship
+from datetime import datetime, timezone
+from database import Base
+
+
+def _utcnow():
+    return datetime.now(timezone.utc)
+
+
+class User(Base):
+    __tablename__ = "users"
+
+    id = Column(Integer, primary_key=True, index=True)
+    username = Column(String, unique=True, nullable=False, index=True)
+    pin_hash = Column(String, nullable=False)
+    password_hash = Column(String, nullable=True)
+    email = Column(String, nullable=True)
+    role = Column(String, nullable=False)  # 'waiter' | 'manager' | 'sysadmin'
+    is_active = Column(Boolean, default=True, nullable=False)
+    full_name = Column(String, nullable=True)
+    nickname = Column(String, nullable=True)
+    mobile_phone = Column(String, nullable=True)
+    avatar_url = Column(String, nullable=True)
+    created_at = Column(DateTime(timezone=True), default=_utcnow)
+
+    orders_opened = relationship("Order", foreign_keys="Order.opened_by", back_populates="opener")
+    orders_closed = relationship("Order", foreign_keys="Order.closed_by", back_populates="closer")
+    order_items = relationship("OrderItem", foreign_keys="OrderItem.added_by", back_populates="added_by_user")
+    items_paid = relationship("OrderItem", foreign_keys="OrderItem.paid_by", back_populates="paid_by_user")
+    order_assignments = relationship("OrderWaiter", back_populates="waiter")
+    zone_assignments = relationship("WaiterZone", back_populates="waiter", cascade="all, delete-orphan")
+
+    primary_assignments = relationship(
+        "AssistantAssignment",
+        foreign_keys="AssistantAssignment.primary_waiter_id",
+        back_populates="primary_waiter",
+    )
+    assistant_assignments = relationship(
+        "AssistantAssignment",
+        foreign_keys="AssistantAssignment.assistant_waiter_id",
+        back_populates="assistant_waiter",
+    )
+
+
+class WaiterZone(Base):
+    """Maps a waiter to a table group they are allowed to operate in.
+    If a waiter has NO rows here, they see NOTHING.
+    A sentinel row with group_id=NULL means 'all zones'."""
+    __tablename__ = "waiter_zones"
+
+    id = Column(Integer, primary_key=True, index=True)
+    waiter_id = Column(Integer, ForeignKey("users.id"), nullable=False)
+    group_id = Column(Integer, ForeignKey("table_groups.id"), nullable=True)  # NULL = all zones
+    assigned_at = Column(DateTime(timezone=True), default=_utcnow)
+
+    waiter = relationship("User", back_populates="zone_assignments")
+    group = relationship("TableGroup", back_populates="waiter_zones")
+
+
+class AssistantAssignment(Base):
+    __tablename__ = "assistant_assignments"
+
+    id = Column(Integer, primary_key=True, index=True)
+    primary_waiter_id = Column(Integer, ForeignKey("users.id"), nullable=False)
+    assistant_waiter_id = Column(Integer, ForeignKey("users.id"), nullable=False)
+    assigned_at = Column(DateTime(timezone=True), default=_utcnow)
+
+    primary_waiter = relationship("User", foreign_keys=[primary_waiter_id], back_populates="primary_assignments")
+    assistant_waiter = relationship("User", foreign_keys=[assistant_waiter_id], back_populates="assistant_assignments")