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/src/services/yookassa.ts

@@ -36,6 +36,37 @@ export async function createHold(params: {
   return res.json() as Promise<YooKassaPayment>
 }
 
+// Immediate charge (capture=true) — for online bookings
+export async function createCharge(params: {
+  shopId: string
+  secretKey: string
+  amount: number
+  description: string
+  returnUrl: string
+  idempotenceKey?: string
+}): Promise<YooKassaPayment> {
+  const auth = Buffer.from(`${params.shopId}:${params.secretKey}`).toString('base64')
+  const res = await fetch('https://api.yookassa.ru/v3/payments', {
+    method: 'POST',
+    headers: {
+      'Authorization': `Basic ${auth}`,
+      'Content-Type': 'application/json',
+      'Idempotence-Key': params.idempotenceKey ?? randomUUID(),
+    },
+    body: JSON.stringify({
+      amount: { value: params.amount.toFixed(2), currency: 'RUB' },
+      capture: true,
+      confirmation: { type: 'redirect', return_url: params.returnUrl },
+      description: params.description,
+    }),
+  })
+  if (!res.ok) {
+    const err = await res.text()
+    throw new Error(`YooKassa error ${res.status}: ${err}`)
+  }
+  return res.json() as Promise<YooKassaPayment>
+}
+
 export async function capturePayment(params: {
   shopId: string
   secretKey: string