fix: unify YooKassa webhook to single URL + add webhook instruction in UI

- Consolidate online booking payment handling into existing /api/webhooks/yookassa
  (was previously split — deposit.ts had partial handling, new route had full)
- deposit.ts webhook now fully handles online_bookings: reserved→confirmed,
  payment_status=paid, paid_amount, WS broadcast, and confirmation email
- Remove POST /api/yookassa/webhook (keep only GET /api/online-bookings/:id)
- PaymentSettingsPage: add webhook URL instruction panel with copy button
  showing https://api.hotelsync.ru/api/webhooks/yookassa and required events

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

src/pages/PaymentSettingsPage.tsx

@@ -411,6 +411,29 @@ export function PaymentSettingsPage() {
                   </button>
                 </div>
               </div>
+              {/* Webhook URL instruction */}
+              <div className="rounded-lg bg-indigo-50 dark:bg-indigo-950/30 border border-indigo-200 dark:border-indigo-800 p-3">
+                <p className="text-xs font-semibold text-indigo-700 dark:text-indigo-300 mb-1">Настройка вебхука в ЮКассе</p>
+                <p className="text-xs text-indigo-600 dark:text-indigo-400 mb-2">
+                  В личном кабинете ЮКассы перейдите: <strong>Настройки → HTTP-уведомления</strong> и укажите этот URL для всех событий:
+                </p>
+                <div className="flex items-center gap-2 bg-white dark:bg-slate-800 rounded-md px-2.5 py-1.5 border border-indigo-200 dark:border-indigo-700">
+                  <code className="text-xs font-mono text-slate-700 dark:text-slate-200 flex-1 break-all">
+                    https://api.hotelsync.ru/api/webhooks/yookassa
+                  </code>
+                  <button
+                    type="button"
+                    onClick={() => navigator.clipboard.writeText('https://api.hotelsync.ru/api/webhooks/yookassa')}
+                    className="text-indigo-400 hover:text-indigo-600 shrink-0"
+                    title="Скопировать"
+                  >
+                    <svg width="13" height="13" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2"><rect x="9" y="9" width="13" height="13" rx="2"/><path d="M5 15H4a2 2 0 0 1-2-2V4a2 2 0 0 1 2-2h9a2 2 0 0 1 2 2v1"/></svg>
+                  </button>
+                </div>
+                <p className="text-[11px] text-indigo-500 dark:text-indigo-400 mt-1.5">
+                  Включите события: <strong>payment.succeeded</strong>, <strong>payment.canceled</strong>, <strong>payment.waiting_for_capture</strong>
+                </p>
+              </div>
             </div>
             <div>
               <p className="text-xs text-slate-500 mb-1.5">Использовать в модулях:</p>