feat: YooKassa webhook, payment timeout, reserved status, BookingConfirmPage

- Add YooKassa webhook handler (POST /api/yookassa/webhook) that updates
  booking to confirmed+paid on payment.succeeded, cancelled on payment.canceled
- Add public status endpoint GET /api/online-bookings/:id for return URL polling
- Add 'reserved' booking status (violet) shown in calendar while awaiting payment
- Add 'website' to BookingSource type
- Payment timeout job (every 2 min) auto-cancels expired unpaid bookings
- Widget setting: "Время ожидания оплаты" (5–60 min, default 15)
- BookingConfirmPage at /booking-confirm/:id — polls status, countdown timer,
  shows success/pending/cancelled state
- Widget bookings now use status='reserved' instead of 'inquiry' when YooKassa
  is configured; set to 'confirmed' by webhook on payment.succeeded
- Migration 070: add 'reserved' to bookings status constraint + payment_expires_at

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

backend/src/app.ts

@@ -45,6 +45,7 @@ import paymentsRoutes from './routes/payments'
 import paymentMethodsRoutes from './routes/paymentMethods'
 import paymentGatewaysRoutes from './routes/paymentGateways'
 import publicWidgetRoutes from './routes/publicWidget'
+import yookassaWebhookRoutes from './routes/yookassaWebhook'
 import { setupAgentWsRoute } from './agent-ws'
 import { startJobs } from './jobs'
 
@@ -142,6 +143,7 @@ export async function buildApp() {
   await fastify.register(paymentMethodsRoutes)
   await fastify.register(paymentGatewaysRoutes)
   await fastify.register(publicWidgetRoutes)
+  await fastify.register(yookassaWebhookRoutes)
   await fastify.register(setupAgentWsRoute)
 
   startJobs()