refactor(billing): rebuild payments list as flat invoice list (tauri parity)

Align /admin/my-payments with the tauri /payments source (per user): the list
is now a flat, newest-first list of the tenant's recorded invoices — one row
per invoice — instead of the per-patient aggregation built from Figma.

Backend:
- replace InvoiceRepository::patientPaymentSummary aggregation with
  tenantInvoices/countTenantInvoices (flat, joins patient name/national code).
- InvoiceService::patientPaymentList → tenantInvoiceList.
- BillingController: GET /api/v1/my/billing/patient-payments →
  GET /api/v1/my/billing/payments returning
  { invoice_uuid, patient_uuid, patient_name, national_code, issued_at,
    amount_rials, status } rows.
- node-2 patient invoices endpoint unchanged.

Frontend:
- useMyPayments: usePatientPayments → usePayments (flat PaymentRow).
- MyPaymentsPage columns match tauri DetailT: row #, avatar+name, national
  code, date-time, amount paid, مشاهده (no status column); 'اضافه کردن بیمار'
  links to /admin/patients/new. Filters (national code / status / Jalali date
  range) kept.

Tests + docs/api/billing.md updated. Intentionally omitted tauri extras:
mobile Cards view and the advanced ModalFilter.

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

src/Billing/Controller/BillingController.php

@@ -157,13 +157,13 @@ class BillingController extends BaseController
     }
 
     /**
-     * لیست پرداخت‌ها — یک ردیف به‌ازای هر بیمار با جمع صورتحساب‌ها.
-     * فیلترها: national_code، status (paid|unsettled|unpaid)، from/to (unix ثانیه).
-     * پاسخ صفحه‌بندی: هر ردیف { patient_uuid, patient_name, national_code,
-     * invoice_count, paid_rials, remaining_rials, status }.
+     * لیست پرداخت‌ها — یک ردیف به‌ازای هر صورتحساب ثبت‌شده‌ی tenant (flat).
+     * فیلترها: national_code، status (paid|unsettled)، from/to (unix ثانیه).
+     * پاسخ صفحه‌بندی: هر ردیف { invoice_uuid, patient_uuid, patient_name,
+     * national_code, issued_at, amount_rials, status }.
      */
-    #[Route('/api/v1/my/billing/patient-payments', methods: ['GET'])]
-    public function listPatientPayments(Request $request, #[CurrentUser] User $user): JsonResponse
+    #[Route('/api/v1/my/billing/payments', methods: ['GET'])]
+    public function listPayments(Request $request, #[CurrentUser] User $user): JsonResponse
     {
         [$entityType, $entityId] = $this->resolveEntity($user);
         if ($entityId === null) {
@@ -179,7 +179,7 @@ class BillingController extends BaseController
         $page  = max(1, (int) $request->query->get('page', 1));
         $limit = min(100, max(1, (int) $request->query->get('limit', 20)));
 
-        $result = $this->invoiceService->patientPaymentList($entityType, $entityId, $filters, $page, $limit);
+        $result = $this->invoiceService->tenantInvoiceList($entityType, $entityId, $filters, $page, $limit);
 
         return $this->paginated($result['items'], $result['total'], $page, $limit);
     }