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/SubscriptionPage.test.tsx

@@ -136,3 +136,49 @@ describe('SubscriptionPage', () => {
     expect(await screen.findByText('در حال حاضر پلنی برای نمایش وجود ندارد.')).toBeInTheDocument();
   });
 });
+
+// ── Tax ────────────────────────────────────────────────────────────────────
+// قیمت دوره خالص است و مالیات رویش می‌نشیند؛ کارت و مودال باید جمع کل را نشان
+// دهند نه قیمت خالص را، وگرنه کاربر سرِ درگاه عدد دیگری می‌بیند.
+
+const TAXED_PLANS = [
+  { uuid: 'p-basic', name: 'basic', level: 1, max_secretaries: 3, max_resources: 3,
+    features: { patient_records: true, services: true, sms_panel: false }, active: true,
+    periods: [
+      { uuid: 'per-1m', label: 'یک ماهه', duration_months: 1, price_rials: 1000000,
+        tax_percent: 10, tax_rials: 100000, payable_rials: 1100000, is_trial: false },
+    ] },
+];
+
+describe('SubscriptionPage — tax', () => {
+  beforeEach(() => { get.mockReset(); mockApi({ plans: TAXED_PLANS }); });
+
+  it('shows the payable amount on the plan card, not the net price', async () => {
+    renderWithProviders(<SubscriptionPage />, { route: '/admin/subscription' });
+    const card = within(await screen.findByTestId('plan-card-basic'));
+
+    expect(card.getByText(formatRial(1100000))).toBeInTheDocument();
+    expect(card.queryByText(formatRial(1000000))).not.toBeInTheDocument();
+    expect(card.getByText(/۱۰٪ مالیات بر ارزش افزوده/)).toBeInTheDocument();
+  });
+
+  it('breaks the price down inside the payment modal', async () => {
+    renderWithProviders(<SubscriptionPage />, { route: '/admin/subscription' });
+    const card = within(await screen.findByTestId('plan-card-basic'));
+    fireEvent.click(card.getByText('تمدید اشتراک'));
+
+    await screen.findByText('پرداخت اشتراک');
+    expect(screen.getByText('قیمت دوره')).toBeInTheDocument();
+    expect(screen.getByText('مالیات بر ارزش افزوده ۱۰٪')).toBeInTheDocument();
+    expect(screen.getByText('جمع کل')).toBeInTheDocument();
+    expect(screen.getAllByText(formatRial(1100000)).length).toBeGreaterThan(0);
+  });
+
+  it('falls back to the net price when the backend sends no tax fields', async () => {
+    mockApi({ plans: PLANS });
+    renderWithProviders(<SubscriptionPage />, { route: '/admin/subscription' });
+    const card = within(await screen.findByTestId('plan-card-basic'));
+
+    expect(card.getByText(formatRial(9000000))).toBeInTheDocument();
+  });
+});