feat: centralized payment gateways + booking widget API

Backend:
- Migration 065: hotel_payment_gateways table (migrates YooKassa from deposit_settings)
- online_bookings table for widget submissions
- Routes: CRUD /api/hotels/:slug/payment-gateways
- Public widget API: /api/widget/:slug/{config,availability,bookings}
- yookassa.ts: add createCharge() for immediate capture

Frontend:
- PaymentSettingsPage: add 'Онлайн-оплата' section with gateway CRUD and module toggles
- DepositSettingsPage: replace YooKassa fields with link to centralized settings
- BookingWidgetPage: connect to real API, show gateway status, real booking submit
- api.ts: add PaymentGateway types, paymentGateways and widget API methods

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

backend/migrations/065_payment_gateways.sql

@@ -0,0 +1,52 @@
+-- Centralized payment gateways (replaces per-module YooKassa config)
+CREATE TABLE IF NOT EXISTS hotel_payment_gateways (
+  id           UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  hotel_id     UUID NOT NULL REFERENCES hotels(id) ON DELETE CASCADE,
+  provider     TEXT NOT NULL DEFAULT 'yookassa', -- yookassa | stripe | tinkoff
+  label        TEXT NOT NULL DEFAULT 'ЮКасса',
+  shop_id      TEXT,
+  secret_key   TEXT,
+  currency     TEXT NOT NULL DEFAULT 'RUB',
+  is_active    BOOLEAN NOT NULL DEFAULT true,
+  -- Which modules use this gateway (JSON array)
+  modules      JSONB NOT NULL DEFAULT '["deposit","booking-widget","room-service"]'::jsonb,
+  created_at   TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+-- Migrate existing YooKassa credentials from hotel_deposit_settings
+INSERT INTO hotel_payment_gateways (hotel_id, provider, label, shop_id, secret_key, currency, modules)
+SELECT
+  hotel_id,
+  'yookassa',
+  'ЮКасса',
+  yookassa_shop_id,
+  yookassa_secret_key,
+  'RUB',
+  '["deposit","booking-widget","room-service"]'::jsonb
+FROM hotel_deposit_settings
+WHERE yookassa_shop_id IS NOT NULL
+ON CONFLICT DO NOTHING;
+
+-- Online bookings table (from widget)
+CREATE TABLE IF NOT EXISTS online_bookings (
+  id              UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  hotel_id        UUID NOT NULL REFERENCES hotels(id) ON DELETE CASCADE,
+  room_id         UUID REFERENCES rooms(id) ON DELETE SET NULL,
+  guest_name      TEXT NOT NULL,
+  guest_email     TEXT,
+  guest_phone     TEXT,
+  check_in        DATE NOT NULL,
+  check_out       DATE NOT NULL,
+  adults          INTEGER NOT NULL DEFAULT 1,
+  children        INTEGER NOT NULL DEFAULT 0,
+  total_amount    NUMERIC(12,2) NOT NULL DEFAULT 0,
+  notes           TEXT,
+  services        JSONB DEFAULT '[]'::jsonb,
+  status          TEXT NOT NULL DEFAULT 'pending', -- pending | paid | confirmed | cancelled
+  payment_method  TEXT DEFAULT 'none',             -- none | yookassa
+  yookassa_payment_id TEXT,
+  yookassa_confirmation_url TEXT,
+  yookassa_status TEXT,
+  booking_id      UUID REFERENCES bookings(id) ON DELETE SET NULL,
+  created_at      TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);