fix(appointment): initiate payment against real gateway endpoint

POST /api/v1/payment/appointment expects { appointment_uuid, gateway,
frontend_address } and returns data.redirect_url. Send that body, redirect
to the gateway URL the backend returns (instead of hand-building one),
align the bank options with the real mellat/sep gateways, and remove the
hard-coded 10,000 toman amount (no real price available at this step).

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

components/appointment/paying/index.js

@@ -11,7 +11,7 @@ function Paying({ setStep, appointmentId }) {
 
   const banks = [
     { id: "mellat", title: "بانک ملت" },
-    { id: "saman", title: "سامان کیش" }
+    { id: "sep", title: "سامان (سپ)" }
   ];
 
   useEffect(() => {
@@ -44,17 +44,16 @@ function Paying({ setStep, appointmentId }) {
     setLoading(true);
     try {
       const paymentPayload = {
-        payment_method: selectedBank,
-        bundle: "appointment",
-        entity_reference_id: appointmentId
+        appointment_uuid: appointmentId,
+        gateway: selectedBank,
+        frontend_address: `${window.location.origin}/payment/result`,
       };
 
-      const response = await request.postPayment(paymentPayload);
+      const res = await request.postAppointmentPayment(paymentPayload);
 
-      // Redirect to payment gateway
-      if (response?.uuid) {
-        const paymentUrl = `${process.env.NEXT_PUBLIC_API_URL}/payment/${response.uuid}`;
-        window.location.href = paymentUrl;
+      const redirectUrl = res?.data?.redirect_url;
+      if (redirectUrl) {
+        window.location.href = redirectUrl;
       } else {
         setStep((prev) => prev + 1);
       }
@@ -114,10 +113,7 @@ function Paying({ setStep, appointmentId }) {
         <span className="bg-[#D7D7D7] hidden md:block h-px w-full mt-[32px] mb-[25px]"></span>
 
         <ButtonFixed>
-          <div className="flex items-center justify-between gap-2">
-            <p className="text-[#616161] md:text-[#3B3B3B] text-[14px] md:text-[16px] font-bold">
-              مبلغ قابل پرداخت : 10،000 تومان
-            </p>
+          <div className="flex items-center justify-end gap-2">
             <Button
               className="!gap-[4px] !mr-auto !flex !px-[12px] !p-[7px] md:!py-[9px] !min-w-[157px]"
               onClick={handlePayment}