feat: Phase 8 SaaS 확장 - 구독관리/결제내역 API 추가

- 사용량 조회 API (GET /subscriptions/usage)
- 데이터 내보내기 API (POST/GET /subscriptions/export)
- 결제 명세서 API (GET /payments/{id}/statement)
- DataExport 모델 및 마이그레이션 추가

app/Services/PaymentService.php

@@ -4,6 +4,7 @@
 
 use App\Models\Tenants\Payment;
 use App\Models\Tenants\Subscription;
+use App\Models\Tenants\Tenant;
 use Illuminate\Contracts\Pagination\LengthAwarePaginator;
 use Illuminate\Support\Facades\DB;
 use Symfony\Component\HttpKernel\Exception\BadRequestHttpException;
@@ -273,4 +274,84 @@ public function refund(int $id, ?string $reason = null): Payment
 
         return $payment->fresh(['subscription.plan']);
     }
+
+    // =========================================================================
+    // 결제 명세서
+    // =========================================================================
+
+    /**
+     * 결제 명세서 조회
+     */
+    public function statement(int $id): array
+    {
+        $tenantId = $this->tenantId();
+
+        // 테넌트 검증 및 결제 조회
+        $subscriptionIds = Subscription::query()
+            ->where('tenant_id', $tenantId)
+            ->pluck('id');
+
+        $payment = Payment::query()
+            ->whereIn('subscription_id', $subscriptionIds)
+            ->with(['subscription.plan'])
+            ->findOrFail($id);
+
+        // 테넌트 정보 조회
+        $tenant = Tenant::findOrFail($tenantId);
+
+        $subscription = $payment->subscription;
+        $plan = $subscription->plan;
+
+        return [
+            'statement_no' => sprintf('INV-%s-%06d', $payment->paid_at?->format('Ymd') ?? now()->format('Ymd'), $payment->id),
+            'issued_at' => now()->toIso8601String(),
+            'payment' => [
+                'id' => $payment->id,
+                'amount' => $payment->amount,
+                'formatted_amount' => $payment->formatted_amount,
+                'payment_method' => $payment->payment_method,
+                'payment_method_label' => $payment->payment_method_label,
+                'transaction_id' => $payment->transaction_id,
+                'status' => $payment->status,
+                'status_label' => $payment->status_label,
+                'paid_at' => $payment->paid_at?->toIso8601String(),
+                'memo' => $payment->memo,
+            ],
+            'subscription' => [
+                'id' => $subscription->id,
+                'started_at' => $subscription->started_at?->toDateString(),
+                'ended_at' => $subscription->ended_at?->toDateString(),
+                'status' => $subscription->status,
+                'status_label' => $subscription->status_label,
+            ],
+            'plan' => $plan ? [
+                'id' => $plan->id,
+                'name' => $plan->name,
+                'code' => $plan->code,
+                'price' => $plan->price,
+                'billing_cycle' => $plan->billing_cycle,
+                'billing_cycle_label' => $plan->billing_cycle_label ?? $plan->billing_cycle,
+            ] : null,
+            'customer' => [
+                'tenant_id' => $tenant->id,
+                'company_name' => $tenant->company_name,
+                'business_number' => $tenant->business_number ?? null,
+                'representative' => $tenant->representative ?? null,
+                'address' => $tenant->address ?? null,
+                'email' => $tenant->email ?? null,
+                'phone' => $tenant->phone ?? null,
+            ],
+            'items' => [
+                [
+                    'description' => $plan ? sprintf('%s 구독 (%s)', $plan->name, $subscription->started_at?->format('Y.m.d') ?? '-') : '구독 서비스',
+                    'quantity' => 1,
+                    'unit_price' => $payment->amount,
+                    'amount' => $payment->amount,
+                ],
+            ],
+            'subtotal' => $payment->amount,
+            'tax' => 0, // VAT 별도 시 계산 필요
+            'total' => $payment->amount,
+        ];
+    }
 }