feat(appointment): redesign payment step with test-mode and real amount

Rebuild the payment screen as a clear confirm-and-pay card: appointment
summary (doctor, patient, Jalali date/time), a prominent amount row
(15,000 تومان from the backend's 150,000 rials), and a countdown with a
progress bar tied to the booking's real expires_at. Fetch
/api/v1/payment/config: in test mode show a 'درگاه آزمایشی' notice and a
'پرداخت آزمایشی' button (gateway select hidden, since the backend forces
MockGateway); otherwise show the bank gateway select. Expired state
offers re-selecting a time.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

services/response.js

@@ -73,6 +73,7 @@ export const request = {
   getMyAppointments: (userId, params) => api.get(`api/v1/appointment/my-appointments/${userId}`, { params, requireAuth: true }),
   postAppointmentPayment: (data) =>
     api.post(`api/v1/payment/appointment`, data, { requireAuth: true }),
+  getPaymentConfig: () => api.get(`api/v1/payment/config`, { requireAuth: true }),
   getPayment: (uuid) => api.get(`api/v1/payment/${uuid}`, { requireAuth: true }),
   getMyPayments: (userId, params) => api.get(`api/v1/payment/my-payments/${userId}`, { params, requireAuth: true }),
   postDoctor: (data) => api.post("api/v1/doctor", data),