feat(payment): enhance Mellat gateway with sandbox support and WSDL configuration

assets/admin/pages/SettingsPage.tsx

@@ -37,6 +37,8 @@ const schema = z.object({
   // payment gateways
   payment_test_mode:  z.string(),
   mellat_enabled:     z.string(),
+  mellat_sandbox:     z.string(),
+  mellat_wsdl_url:    z.string(),
   mellat_terminal_id: z.string(),
   mellat_username:    z.string(),
   mellat_password:    z.string(),
@@ -65,6 +67,8 @@ const toForm = (s: Partial<Settings>): FormValues => ({
   appointment_fee_rials:          s.appointment_fee_rials ?? '150000',
   payment_test_mode:              s.payment_test_mode ?? '0',
   mellat_enabled:                 s.mellat_enabled ?? '1',
+  mellat_sandbox:                 s.mellat_sandbox ?? '0',
+  mellat_wsdl_url:                s.mellat_wsdl_url ?? '',
   mellat_terminal_id:             s.mellat_terminal_id ?? '',
   mellat_username:                s.mellat_username ?? '',
   mellat_password:                s.mellat_password ?? '',
@@ -202,6 +206,7 @@ export default function SettingsPage() {
 
   const paymentTestMode          = watch('payment_test_mode') === '1';
   const mellatEnabled            = watch('mellat_enabled') === '1';
+  const mellatSandbox            = watch('mellat_sandbox') === '1';
   const sepEnabled               = watch('sep_enabled') === '1';
   const apptCommissionEnabled    = watch('appointment_commission_enabled') === '1';
   const upgradeCommissionEnabled = watch('upgrade_commission_enabled') === '1';
@@ -423,6 +428,15 @@ export default function SettingsPage() {
                       </div>
                     </Field>
                   </div>
+                  <div className="settings-grid" style={{ gridTemplateColumns: '1fr auto', alignItems: 'end', marginTop: 12 }}>
+                    <Field label="آدرس WSDL (اختیاری — خالی = عملیاتی)">
+                      <input {...register('mellat_wsdl_url')} className="input" dir="ltr" placeholder="https://bpm.shaparak.ir/pgwchannel/services/pgw?wsdl" />
+                    </Field>
+                    <div className="gw-state" style={{ color: mellatSandbox ? 'var(--warning)' : 'var(--text-3)' }}>
+                      {mellatSandbox ? 'Sandbox (آزمایشگاه)' : 'واقعی'}
+                      <Toggle checked={mellatSandbox} onChange={() => toggle('mellat_sandbox', mellatSandbox)} label="حالت Sandbox ملت" />
+                    </div>
+                  </div>
                 </div>
 
                 {/* سپ */}