feat: TenantStatField API 구현

- TenantStatFieldService: CRUD + reorder + bulkUpsert 로직 구현
- TenantStatFieldController: 7개 엔드포인트 (SAM API Rules 준수)
- FormRequest: Store/Update 검증 클래스 생성
- Swagger: 완전한 API 문서화 (6개 스키마, 7개 엔드포인트)
- i18n: message.tenant_stat_field 키 추가
- Route: /tenant-stat-fields 7개 라우트 등록

유니크 제약 검증: tenant_id + target_table + field_key
집계 함수 필터링: avg, sum, min, max, count

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

@@ -0,0 +1,75 @@
+<?php
+
+namespace App\Http\Controllers\Api\V1;
+
+use App\Helpers\ApiResponse;
+use App\Http\Controllers\Controller;
+use App\Http\Requests\TenantStatField\TenantStatFieldStoreRequest;
+use App\Http\Requests\TenantStatField\TenantStatFieldUpdateRequest;
+use App\Services\TenantStatFieldService;
+use Illuminate\Http\Request;
+
+class TenantStatFieldController extends Controller
+{
+    public function __construct(private TenantStatFieldService $service) {}
+
+    // GET /tenant-stat-fields
+    public function index(Request $request)
+    {
+        return ApiResponse::handle(function () use ($request) {
+            return $this->service->index($request->all());
+        }, __('message.tenant_stat_field.fetched'));
+    }
+
+    // POST /tenant-stat-fields
+    public function store(TenantStatFieldStoreRequest $request)
+    {
+        return ApiResponse::handle(function () use ($request) {
+            return $this->service->store($request->validated());
+        }, __('message.tenant_stat_field.created'));
+    }
+
+    // GET /tenant-stat-fields/{id}
+    public function show(int $id)
+    {
+        return ApiResponse::handle(function () use ($id) {
+            return $this->service->show($id);
+        }, __('message.tenant_stat_field.fetched'));
+    }
+
+    // PATCH /tenant-stat-fields/{id}
+    public function update(int $id, TenantStatFieldUpdateRequest $request)
+    {
+        return ApiResponse::handle(function () use ($id, $request) {
+            return $this->service->update($id, $request->validated());
+        }, __('message.tenant_stat_field.updated'));
+    }
+
+    // DELETE /tenant-stat-fields/{id}
+    public function destroy(int $id)
+    {
+        return ApiResponse::handle(function () use ($id) {
+            $this->service->destroy($id);
+
+            return 'success';
+        }, __('message.tenant_stat_field.deleted'));
+    }
+
+    // POST /tenant-stat-fields/reorder
+    public function reorder(Request $request)
+    {
+        return ApiResponse::handle(function () use ($request) {
+            $this->service->reorder($request->input());
+
+            return 'success';
+        }, __('message.tenant_stat_field.reordered'));
+    }
+
+    // PUT /tenant-stat-fields/bulk-upsert
+    public function bulkUpsert(Request $request)
+    {
+        return ApiResponse::handle(function () use ($request) {
+            return $this->service->bulkUpsert($request->input('items', []));
+        }, __('message.tenant_stat_field.bulk_upsert'));
+    }
+}