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/types/index.ts

@@ -574,7 +574,13 @@ export interface SubscriptionPeriod {
     uuid: string;
     label: string;
     duration_months: number;
+    /** قیمت خالص، بدون مالیات. */
     price_rials: number;
+    /** درصد مالیات؛ با مالیاتِ خاموش برابر صفر. */
+    tax_percent: number;
+    tax_rials: number;
+    /** قیمت خالص + مالیات — مبلغی که واقعاً پرداخت می‌شود. */
+    payable_rials: number;
     is_trial: boolean;
 }