feat:문서관리 Phase 4.1 - DocumentTemplate API + 결재 워크플로우 활성화

- DocumentTemplate 모델 6개 생성 (Template, ApprovalLine, BasicField, Section, SectionItem, Column)
- DocumentTemplateService (list/show) + DocumentTemplateController (index/show)
- GET /v1/document-templates, GET /v1/document-templates/{id} 라우트
- DocumentTemplateApi.php Swagger (7개 스키마, 2개 엔드포인트)
- Document 결재 워크플로우 4개 엔드포인트 활성화 (submit/approve/reject/cancel)
- ApproveRequest, RejectRequest FormRequest 생성
- DocumentApi.php Swagger에 결재 엔드포인트 4개 추가
- Document.template() 참조 경로 수정 (DocumentTemplate → Documents 네임스페이스)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/Http/Controllers/Api/V1/Documents/DocumentController.php

@@ -4,7 +4,9 @@
 
 use App\Helpers\ApiResponse;
 use App\Http\Controllers\Controller;
+use App\Http\Requests\Document\ApproveRequest;
 use App\Http\Requests\Document\IndexRequest;
+use App\Http\Requests\Document\RejectRequest;
 use App\Http\Requests\Document\StoreRequest;
 use App\Http\Requests\Document\UpdateRequest;
 use App\Services\DocumentService;
@@ -70,10 +72,50 @@ public function destroy(int $id): JsonResponse
     }
 
     // =========================================================================
-    // 결재 관련 메서드 (보류 - 기존 시스템 연동 필요)
+    // 결재 워크플로우
     // =========================================================================
-    // public function submit(int $id): JsonResponse
-    // public function approve(int $id, ApproveRequest $request): JsonResponse
-    // public function reject(int $id, RejectRequest $request): JsonResponse
-    // public function cancel(int $id): JsonResponse
+
+    /**
+     * 결재 제출 (DRAFT → PENDING)
+     * POST /v1/documents/{id}/submit
+     */
+    public function submit(int $id): JsonResponse
+    {
+        return ApiResponse::handle(function () use ($id) {
+            return $this->service->submit($id);
+        }, __('message.updated'));
+    }
+
+    /**
+     * 결재 승인
+     * POST /v1/documents/{id}/approve
+     */
+    public function approve(int $id, ApproveRequest $request): JsonResponse
+    {
+        return ApiResponse::handle(function () use ($id, $request) {
+            return $this->service->approve($id, $request->validated()['comment'] ?? null);
+        }, __('message.updated'));
+    }
+
+    /**
+     * 결재 반려
+     * POST /v1/documents/{id}/reject
+     */
+    public function reject(int $id, RejectRequest $request): JsonResponse
+    {
+        return ApiResponse::handle(function () use ($id, $request) {
+            return $this->service->reject($id, $request->validated()['comment']);
+        }, __('message.updated'));
+    }
+
+    /**
+     * 결재 취소/회수
+     * POST /v1/documents/{id}/cancel
+     */
+    public function cancel(int $id): JsonResponse
+    {
+        return ApiResponse::handle(function () use ($id) {
+            return $this->service->cancel($id);
+        }, __('message.updated'));
+    }
 }