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/PlanController.php

@@ -0,0 +1,88 @@
+<?php
+
+namespace App\Http\Controllers\Api\V1;
+
+use App\Http\Controllers\Controller;
+use App\Http\Requests\V1\Plan\PlanIndexRequest;
+use App\Http\Requests\V1\Plan\PlanStoreRequest;
+use App\Http\Requests\V1\Plan\PlanUpdateRequest;
+use App\Http\Response\ApiResponse;
+use App\Services\PlanService;
+use Illuminate\Http\JsonResponse;
+
+class PlanController extends Controller
+{
+    public function __construct(
+        private readonly PlanService $planService
+    ) {}
+
+    /**
+     * 요금제 목록 (관리자용)
+     */
+    public function index(PlanIndexRequest $request): JsonResponse
+    {
+        $result = $this->planService->index($request->validated());
+
+        return ApiResponse::handle('message.fetched', $result);
+    }
+
+    /**
+     * 활성 요금제 목록 (공개용)
+     */
+    public function active(): JsonResponse
+    {
+        $result = $this->planService->active();
+
+        return ApiResponse::handle('message.fetched', $result);
+    }
+
+    /**
+     * 요금제 등록
+     */
+    public function store(PlanStoreRequest $request): JsonResponse
+    {
+        $result = $this->planService->store($request->validated());
+
+        return ApiResponse::handle('message.created', $result, 201);
+    }
+
+    /**
+     * 요금제 상세
+     */
+    public function show(int $id): JsonResponse
+    {
+        $result = $this->planService->show($id);
+
+        return ApiResponse::handle('message.fetched', $result);
+    }
+
+    /**
+     * 요금제 수정
+     */
+    public function update(PlanUpdateRequest $request, int $id): JsonResponse
+    {
+        $result = $this->planService->update($id, $request->validated());
+
+        return ApiResponse::handle('message.updated', $result);
+    }
+
+    /**
+     * 요금제 삭제
+     */
+    public function destroy(int $id): JsonResponse
+    {
+        $this->planService->destroy($id);
+
+        return ApiResponse::handle('message.deleted');
+    }
+
+    /**
+     * 요금제 활성/비활성 토글
+     */
+    public function toggle(int $id): JsonResponse
+    {
+        $result = $this->planService->toggle($id);
+
+        return ApiResponse::handle('message.updated', $result);
+    }
+}