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

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

app/Http/Resources/Api/Admin/OrderResource.php

@@ -2,6 +2,7 @@
 
 namespace App\Http\Resources\Api\Admin;
 
+use App\Support\Billing\BillingDuplicateDetector;
 use Illuminate\Http\Request;
 use Illuminate\Http\Resources\Json\JsonResource;
 
@@ -12,6 +13,7 @@ class OrderResource extends JsonResource
         return [
             'id' => $this->id,
             'order_num' => $this->order_num,
+            'duplicate' => BillingDuplicateDetector::forOrder($this->id),
             'customer' => $this->whenLoaded('customer', fn() => [
                 'id'       => $this->customer->id,
                 'uuid'     => $this->customer->uuid,
@@ -95,6 +97,7 @@ class OrderResource extends JsonResource
             ])),
             'sub_total'       => $this->sub_total,
             'discount_amount' => $this->discount_amount,
+            'coupon_code'     => $this->coupon_code,
             'total'           => $this->total,
             // Order has no payment_id FK — `payment` relation is always null. Fall back to
             // the raw payment_method string instead of letting whenLoaded() mask it with null.