feat: implement tax calculations for subscription and SMS wallet payments

- Updated SubscriptionPeriod interface to include tax-related fields: tax_percent, tax_rials, and payable_rials.
- Modified payment API documentation to reflect changes in tax handling for subscriptions and SMS wallet charges.
- Adjusted PaymentController to calculate payment amounts based on subscription period details instead of client input.
- Enhanced PaymentManager to handle net amounts for SMS wallet charges, ensuring tax is not credited to the wallet.
- Created PaymentTaxCalculator and SubscriptionTaxCalculator services to manage tax calculations consistently across payment types.
- Added tests for tax calculations in both subscription and SMS wallet contexts, ensuring correct behavior with and without tax enabled.
- Updated frontend components to display tax information appropriately during payment processes.

assets/admin/pages/SmsWalletPage.tsx

@@ -66,7 +66,7 @@ function SmsWalletPageInner() {
     queryFn: () => api.get('/api/v1/sms/settings'),
   });
 
-  const { isTestMode } = usePaymentConfig();
+  const { isTestMode, taxPercent } = usePaymentConfig();
 
   const balance     = balanceData?.data;
   const logs        = logsData?.data ?? EMPTY_LOGS;
@@ -76,6 +76,12 @@ function SmsWalletPageInner() {
   const chargeForm = useForm<ChargeForm>({ resolver: zodResolver(chargeSchema) });
   const watchAmount = chargeForm.watch('amount_rials');
 
+  // مبلغِ واردشده خالص است — همان چیزی که به کیف پول می‌نشیند. مالیات رویش اضافه
+  // می‌شود، دقیقاً با همان فرمولِ بک‌اند، تا عددِ مودال با صفحهٔ بانک یکی باشد.
+  const chargeNet     = tomanToRial(Number(watchAmount) || 0);
+  const chargeTax     = Math.round(chargeNet * taxPercent / 100);
+  const chargePayable = chargeNet + chargeTax;
+
   const chargeMutation = useMutation({
     mutationFn: ({ amount_rials }: ChargeForm) =>
       api.post<{ data: { payment_url: string } }>('/api/v1/sms/wallet/charge', {
@@ -548,6 +554,31 @@ function SmsWalletPageInner() {
               )}
             </div>
 
+            {watchAmount && Number(watchAmount) >= 1000 && taxPercent > 0 && (
+              <div style={{
+                display: 'flex', flexDirection: 'column', gap: 6,
+                background: 'var(--surface-2)', borderRadius: 8,
+                padding: '10px 14px', fontSize: 13, color: 'var(--text-2)',
+              }}>
+                <div style={{ display: 'flex', justifyContent: 'space-between' }}>
+                  <span>اعتباری که به کیف پول اضافه می‌شود</span>
+                  <span style={{ direction: 'ltr' }}>{formatRial(chargeNet)}</span>
+                </div>
+                <div style={{ display: 'flex', justifyContent: 'space-between' }}>
+                  <span>مالیات بر ارزش افزوده {formatNumber(taxPercent)}٪</span>
+                  <span style={{ direction: 'ltr' }}>{formatRial(chargeTax)}</span>
+                </div>
+                <div style={{
+                  display: 'flex', justifyContent: 'space-between',
+                  borderTop: '1px solid var(--border)', paddingTop: 6,
+                  color: 'var(--text)', fontWeight: 700,
+                }}>
+                  <span>مبلغ قابل پرداخت</span>
+                  <span style={{ direction: 'ltr' }}>{formatRial(chargePayable)}</span>
+                </div>
+              </div>
+            )}
+
             {watchAmount && Number(watchAmount) >= 1000 && (
               <div style={{
                 background: isTestMode ? 'var(--warning-bg)' : 'var(--primary-soft)',
@@ -556,8 +587,8 @@ function SmsWalletPageInner() {
                 fontSize: 13, color: isTestMode ? 'var(--warning)' : 'var(--primary)', fontWeight: 500,
               }}>
                 {isTestMode
-                  ? `پرداخت آزمایشی ${formatRial(tomanToRial(Number(watchAmount)))}`
-                  : `پرداخت ${formatRial(tomanToRial(Number(watchAmount)))} از طریق ${gateway === 'mellat' ? 'بانک ملت' : 'سپ'}`
+                  ? `پرداخت آزمایشی ${formatRial(chargePayable)}`
+                  : `پرداخت ${formatRial(chargePayable)} از طریق ${gateway === 'mellat' ? 'بانک ملت' : 'سپ'}`
                 }
               </div>
             )}