feat: housekeeping automation — auto-task on checkout + room status on done

Backend:
- Migration 023: housekeeping_settings table (checkout_auto, checkout_priority, inspection_after_clean)
- New route: GET/PATCH /api/hotels/:slug/housekeeping-settings
- bookings.ts: on checked_out → auto-create turnover task + mark room dirty + broadcast WS
- housekeeping.ts: on task done → update room status (inspect|clean per setting) + broadcast WS
- ws.ts: export broadcast() for use in other routes

Frontend:
- HousekeepingPage: load/save settings to API, live Loader on save button
- useHotelSocket: add housekeeping WS message types
- HousekeepingPage: subscribe to WS — new tasks appear instantly without refresh
- BookingModal: show total section when room + nights selected (not just when total > 0)

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

backend/migrations/023_housekeeping_settings.sql

@@ -0,0 +1,7 @@
+CREATE TABLE IF NOT EXISTS housekeeping_settings (
+  hotel_id               UUID    PRIMARY KEY REFERENCES hotels(id) ON DELETE CASCADE,
+  checkout_auto          BOOLEAN NOT NULL DEFAULT true,
+  checkout_priority      VARCHAR(10) NOT NULL DEFAULT 'high',
+  inspection_after_clean BOOLEAN NOT NULL DEFAULT true,
+  updated_at             TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);