feat: 구독/결제 API 확장 (Plan, Subscription, Payment)

- Plan/Subscription/Payment 모델에 상태 상수, 스코프, 헬퍼 메서드 추가
- PlanService, SubscriptionService, PaymentService 생성
- PlanController, SubscriptionController, PaymentController 생성
- FormRequest 9개 생성 (Plan 3개, Subscription 3개, Payment 3개)
- Swagger 문서 3개 생성 (PlanApi, SubscriptionApi, PaymentApi)
- API 라우트 22개 등록 (Plan 7개, Subscription 8개, Payment 7개)
- Pint 코드 스타일 정리

app/Http/Controllers/Api/V1/SubscriptionController.php

@@ -0,0 +1,98 @@
+<?php
+
+namespace App\Http\Controllers\Api\V1;
+
+use App\Http\Controllers\Controller;
+use App\Http\Requests\V1\Subscription\SubscriptionCancelRequest;
+use App\Http\Requests\V1\Subscription\SubscriptionIndexRequest;
+use App\Http\Requests\V1\Subscription\SubscriptionStoreRequest;
+use App\Http\Response\ApiResponse;
+use App\Services\SubscriptionService;
+use Illuminate\Http\JsonResponse;
+
+class SubscriptionController extends Controller
+{
+    public function __construct(
+        private readonly SubscriptionService $subscriptionService
+    ) {}
+
+    /**
+     * 구독 목록
+     */
+    public function index(SubscriptionIndexRequest $request): JsonResponse
+    {
+        $result = $this->subscriptionService->index($request->validated());
+
+        return ApiResponse::handle('message.fetched', $result);
+    }
+
+    /**
+     * 현재 활성 구독
+     */
+    public function current(): JsonResponse
+    {
+        $result = $this->subscriptionService->current();
+
+        return ApiResponse::handle('message.fetched', $result);
+    }
+
+    /**
+     * 구독 등록
+     */
+    public function store(SubscriptionStoreRequest $request): JsonResponse
+    {
+        $result = $this->subscriptionService->store($request->validated());
+
+        return ApiResponse::handle('message.created', $result, 201);
+    }
+
+    /**
+     * 구독 상세
+     */
+    public function show(int $id): JsonResponse
+    {
+        $result = $this->subscriptionService->show($id);
+
+        return ApiResponse::handle('message.fetched', $result);
+    }
+
+    /**
+     * 구독 취소
+     */
+    public function cancel(SubscriptionCancelRequest $request, int $id): JsonResponse
+    {
+        $result = $this->subscriptionService->cancel($id, $request->validated()['reason'] ?? null);
+
+        return ApiResponse::handle('message.subscription.cancelled', $result);
+    }
+
+    /**
+     * 구독 갱신
+     */
+    public function renew(SubscriptionStoreRequest $request, int $id): JsonResponse
+    {
+        $result = $this->subscriptionService->renew($id, $request->validated());
+
+        return ApiResponse::handle('message.subscription.renewed', $result);
+    }
+
+    /**
+     * 구독 일시정지
+     */
+    public function suspend(int $id): JsonResponse
+    {
+        $result = $this->subscriptionService->suspend($id);
+
+        return ApiResponse::handle('message.subscription.suspended', $result);
+    }
+
+    /**
+     * 구독 재개
+     */
+    public function resume(int $id): JsonResponse
+    {
+        $result = $this->subscriptionService->resume($id);
+
+        return ApiResponse::handle('message.subscription.resumed', $result);
+    }
+}