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/services/reservation_tasks.py

@@ -0,0 +1,48 @@
+"""Background task: auto-mark overdue pending reservations as no_show."""
+import asyncio
+import logging
+from datetime import datetime, timezone, timedelta
+
+logger = logging.getLogger(__name__)
+
+# Grace period after reserved_for before a pending reservation becomes no_show
+NO_SHOW_GRACE_MINUTES = 30
+
+# How often the checker runs
+CHECK_INTERVAL_SECONDS = 300  # 5 minutes
+
+
+async def _run_no_show_checker():
+    # Import here to avoid circular imports at module load time
+    from database import SessionLocal
+    from models.reservation import Reservation
+
+    while True:
+        await asyncio.sleep(CHECK_INTERVAL_SECONDS)
+        try:
+            db = SessionLocal()
+            try:
+                cutoff = datetime.now(timezone.utc) - timedelta(minutes=NO_SHOW_GRACE_MINUTES)
+                overdue = (
+                    db.query(Reservation)
+                    .filter(
+                        Reservation.status == "pending",
+                        Reservation.reserved_for < cutoff,
+                    )
+                    .all()
+                )
+                if overdue:
+                    for r in overdue:
+                        r.status = "no_show"
+                        r.updated_at = datetime.now(timezone.utc)
+                    db.commit()
+                    logger.info("no_show_checker: marked %d reservation(s) as no_show", len(overdue))
+            finally:
+                db.close()
+        except Exception:
+            logger.exception("no_show_checker: unexpected error")
+
+
+async def start_reservation_tasks() -> asyncio.Task:
+    task = asyncio.create_task(_run_no_show_checker())
+    return task