feat(billing): renewals, coupons, VAT numbering, billing cycles and invoice payment tracking

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

app/Repositories/Api/Invoice/InvoiceRepository.php

@@ -8,6 +8,7 @@ use App\Models\Invoice;
 use App\Models\InvoiceItem;
 use App\Models\Order;
 use App\Repositories\Api\BaseApiRepository;
+use App\Support\VatNumbering;
 
 class InvoiceRepository extends BaseApiRepository implements InvoiceRepositoryInterface
 {
@@ -37,6 +38,7 @@ class InvoiceRepository extends BaseApiRepository implements InvoiceRepositoryIn
             // sub_total là tổng TRƯỚC giảm giá, để sub_total - discount_amount = total.
             'sub_total'       => (int) $order->total + $discount,
             'discount_amount' => $discount,
+            'coupon_code'     => $order->coupon_code,
             'tax'             => 0,
             'total'           => $order->total,
             'status'          => InvoiceStatus::UNPAID->value,
@@ -78,7 +80,7 @@ class InvoiceRepository extends BaseApiRepository implements InvoiceRepositoryIn
             }
         }
 
-        return $invoice;
+        return VatNumbering::settle($invoice);
     }
 
     // -------------------------------------------------------------------------