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/message.py

@@ -0,0 +1,48 @@
+from sqlalchemy import Column, Integer, String, DateTime, ForeignKey, Text, Boolean
+from sqlalchemy.orm import relationship
+from datetime import datetime, timezone
+from database import Base
+
+
+def _utcnow():
+    return datetime.now(timezone.utc)
+
+
+class QuickMessageTemplate(Base):
+    """Manager-configurable quick message templates."""
+    __tablename__ = "quick_message_templates"
+
+    id = Column(Integer, primary_key=True, index=True)
+    body = Column(String, nullable=False)
+    sort_order = Column(Integer, default=0, nullable=False)
+    is_active = Column(Boolean, default=True, nullable=False)
+    created_at = Column(DateTime(timezone=True), default=_utcnow)
+
+
+class StaffMessage(Base):
+    """A message sent from a manager to one or more waiters."""
+    __tablename__ = "staff_messages"
+
+    id = Column(Integer, primary_key=True, index=True)
+    sender_id = Column(Integer, ForeignKey("users.id"), nullable=False)
+    body = Column(Text, nullable=False)
+    # JSON arrays stored as text: "[1,2,3]" for waiter ids, "[5,6]" for table ids
+    target_waiter_ids = Column(Text, nullable=False, default="[]")
+    table_ids = Column(Text, nullable=False, default="[]")
+    created_at = Column(DateTime(timezone=True), default=_utcnow)
+
+    sender = relationship("User", foreign_keys=[sender_id])
+    acks = relationship("StaffMessageAck", back_populates="message", cascade="all, delete-orphan")
+
+
+class StaffMessageAck(Base):
+    """Acknowledgement by a specific waiter for a specific message."""
+    __tablename__ = "staff_message_acks"
+
+    id = Column(Integer, primary_key=True, index=True)
+    message_id = Column(Integer, ForeignKey("staff_messages.id"), nullable=False)
+    waiter_id = Column(Integer, ForeignKey("users.id"), nullable=False)
+    acked_at = Column(DateTime(timezone=True), default=_utcnow)
+
+    message = relationship("StaffMessage", back_populates="acks")
+    waiter = relationship("User")