feat: full Room Service backend integration

- Migrations 086-088: room_service_settings, menu_items, orders+order_items
- Backend: /api/hotels/:slug/room-service/* routes (settings, menu CRUD,
  orders CRUD, public config, public order status)
- push.ts: sendPushToHotel() — push to all hotel staff on new order
- On new order: in-app notification + push to hotel staff
- api.ts: RoomService types + roomService API methods
- RoomServicePage: replaced mocked state with real API, 30s polling,
  add/edit/delete menu items modal, real advance/cancel order
- GuestRoomServicePage: fetches real menu + config, uses hotel payment
  methods, submits real order, polls status every 15s

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

backend/migrations/088_room_service_orders.sql

@@ -0,0 +1,32 @@
+-- Migration 088 — Room Service: orders & order items
+
+CREATE TABLE room_service_orders (
+  id             UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  hotel_id       UUID NOT NULL REFERENCES hotels(id) ON DELETE CASCADE,
+  room_number    TEXT NOT NULL,
+  guest_name     TEXT NOT NULL DEFAULT '',
+  order_type     TEXT NOT NULL DEFAULT 'room' CHECK (order_type IN ('room', 'restaurant')),
+  scheduled_time TEXT,
+  status         TEXT NOT NULL DEFAULT 'new'
+                   CHECK (status IN ('new','preparing','ready','delivered','cancelled')),
+  payment_method TEXT,      -- name from hotel_payment_methods (snapshot)
+  subtotal       NUMERIC(10,2) NOT NULL DEFAULT 0,
+  service_charge NUMERIC(10,2) NOT NULL DEFAULT 0,
+  total          NUMERIC(10,2) NOT NULL DEFAULT 0,
+  notes          TEXT,
+  created_at     TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+  updated_at     TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE TABLE room_service_order_items (
+  id           UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  order_id     UUID NOT NULL REFERENCES room_service_orders(id) ON DELETE CASCADE,
+  menu_item_id UUID REFERENCES room_service_menu_items(id) ON DELETE SET NULL,
+  name         TEXT NOT NULL,
+  emoji        TEXT NOT NULL DEFAULT '🍽️',
+  price        NUMERIC(10,2) NOT NULL,
+  quantity     INTEGER NOT NULL DEFAULT 1
+);
+
+CREATE INDEX ON room_service_orders(hotel_id, status);
+CREATE INDEX ON room_service_orders(hotel_id, created_at DESC);