feat: enrich invoice summary with session payments, consumables and discount

Port the remaining gap of tauri /files/invoice-summary into the admin
invoice summary: GET /api/v1/billing/invoices/{uuid} now includes a
'session' key (full PatientSession payload) so InvoiceSummaryModal can
render the consumables table, the itemized payments table (method,
amount, date-time, recorder) and real discount/paid/remaining figures
instead of heuristics. Invoices without a source session keep the
previous behavior (session: null).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/Billing/Controller/BillingController.php

@@ -139,7 +139,7 @@ class BillingController extends BaseController
             return $this->error(ErrorCodes::ERR_NOT_FOUND_001, 'صورتحساب یافت نشد', 404);
         }
 
-        return $this->success(['data' => $invoice->toArray()]);
+        return $this->success(['data' => $this->invoiceService->detailWithSession($invoice)]);
     }
 
     #[Route('/api/v1/billing/invoices/{uuid}/finalize', methods: ['POST'])]

src/Billing/Service/InvoiceService.php

@@ -9,6 +9,7 @@ use App\Billing\ValueObject\Money;
 use App\ClinicService\Service\TariffService;
 use App\Insurance\Service\TenantInsuranceService;
 use App\Patient\Entity\PatientSession;
+use App\Patient\Repository\PatientSessionRepository;
 
 class InvoiceService
 {
@@ -17,6 +18,7 @@ class InvoiceService
         private readonly TariffService            $tariffService,
         private readonly TenantInsuranceService   $tenantInsuranceService,
         private readonly BillingCalculator        $calculator,
+        private readonly PatientSessionRepository $sessionRepo,
     ) {}
 
     /**
@@ -75,6 +77,22 @@ class InvoiceService
         $this->invoiceRepo->save($invoice);
     }
 
+    /**
+     * Invoice detail enriched with its source encounter (`session` key):
+     * payments, consumables, discount and paid totals for the invoice summary
+     * view. `session` is null for invoices not created from a session.
+     */
+    public function detailWithSession(Invoice $invoice): array
+    {
+        $data = $invoice->toArray();
+
+        $sessionId = $data['patient_session_id'];
+        $session   = $sessionId !== null ? $this->sessionRepo->find($sessionId) : null;
+        $data['session'] = $session?->toArray();
+
+        return $data;
+    }
+
     /**
      * Paginated flat list of a tenant's recorded (finalized/paid) invoices for
      * the payments list (node 1). Rows arrive ready-shaped from the repository;