Connect ChannelsPage, FloorMapPage, SettingsPage, UsersPage to real API

- ChannelsPage: load from API, toggle/sync call real endpoints; normalize
  enabled→isEnabled, lastSyncedAt→lastSyncAt, add displayName/mappings defaults
- FloorMapPage: load rooms+bookings from API; create booking via API
- SettingsPage: load hotel via GET /api/hotels/:slug; save general section
  via PATCH (name, address, timezone, currency, check_in/out times)
- UsersPage: load users from API; create/update/delete via API;
  map backend User (name/role) → StaffUser (firstName/lastName/StaffRole)
- api.ts: add hotels.get/update, users.delete, channel normalization,
  HotelPayload/toHotelPayload
- types/index.ts: extend Hotel with phone/checkInTime/checkOutTime/optional fields;
  add User.createdAt/updatedAt
- backend/routes/hotels.ts: extend PATCH to allow address/phone/check_in_time/check_out_time
- backend/migrations/004_hotels_contacts.sql: add address/phone/check_in/out_time to hotels

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

src/pages/AdminDashboard.tsx

@@ -5,7 +5,7 @@ import { Badge } from '../components/ui/Badge'
 
 export function AdminDashboard() {
   const activeHotels = MOCK_HOTELS.filter(h => h.isActive).length
-  const totalRooms = MOCK_HOTELS.reduce((s, h) => s + h.roomCount, 0)
+  const totalRooms = MOCK_HOTELS.reduce((s, h) => s + (h.roomCount ?? 0), 0)
 
   return (
     <div className="p-4 md:p-6 space-y-6">