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/087_room_service_menu.sql

@@ -0,0 +1,18 @@
+-- Migration 087 — Room Service: menu items
+
+CREATE TABLE room_service_menu_items (
+  id           UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  hotel_id     UUID NOT NULL REFERENCES hotels(id) ON DELETE CASCADE,
+  name         TEXT NOT NULL,
+  category     TEXT NOT NULL DEFAULT 'Основные',
+  price        NUMERIC(10,2) NOT NULL,
+  emoji        TEXT NOT NULL DEFAULT '🍽️',
+  prep_time_min INTEGER NOT NULL DEFAULT 15,
+  is_popular   BOOLEAN NOT NULL DEFAULT false,
+  is_stop_list BOOLEAN NOT NULL DEFAULT false,
+  is_active    BOOLEAN NOT NULL DEFAULT true,
+  sort_order   INTEGER NOT NULL DEFAULT 0,
+  created_at   TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX ON room_service_menu_items(hotel_id, is_active);