feat: [문서] rendered_html 스냅샷 저장 + snapshot 엔드포인트

- Document upsert에 rendered_html 필드 추가
- Lazy Snapshot API (snapshot_document_id resolve)
- UpsertRequest rendered_html 검증 추가
- DocumentTemplateSection description 컬럼

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

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

@@ -74,6 +74,22 @@ public function destroy(int $id): JsonResponse
         }, __('message.deleted'));
     }
 
+    /**
+     * rendered_html 스냅샷 저장 (Lazy Snapshot)
+     * PATCH /v1/documents/{id}/snapshot
+     */
+    public function patchSnapshot(int $id, UpdateRequest $request): JsonResponse
+    {
+        return ApiResponse::handle(function () use ($id, $request) {
+            $renderedHtml = $request->validated()['rendered_html'] ?? null;
+            if (! $renderedHtml) {
+                throw new \Symfony\Component\HttpKernel\Exception\BadRequestHttpException('rendered_html is required');
+            }
+
+            return $this->service->patchSnapshot($id, $renderedHtml);
+        }, __('message.updated'));
+    }
+
     // =========================================================================
     // FQC 일괄생성 (제품검사)
     // =========================================================================

app/Http/Requests/Document/StoreRequest.php

@@ -28,6 +28,9 @@ public function rules(): array
             'approvers.*.user_id' => 'required_with:approvers|integer|exists:users,id',
             'approvers.*.role' => 'nullable|string|max:50',
 
+            // HTML 스냅샷
+            'rendered_html' => 'nullable|string',
+
             // 문서 데이터 (EAV)
             'data' => 'nullable|array',
             'data.*.section_id' => 'nullable|integer',

app/Http/Requests/Document/UpdateRequest.php

@@ -27,6 +27,9 @@ public function rules(): array
             'approvers.*.user_id' => 'required_with:approvers|integer|exists:users,id',
             'approvers.*.role' => 'nullable|string|max:50',
 
+            // HTML 스냅샷
+            'rendered_html' => 'nullable|string',
+
             // 문서 데이터 (EAV)
             'data' => 'nullable|array',
             'data.*.section_id' => 'nullable|integer',

app/Http/Requests/Document/UpsertRequest.php

@@ -30,6 +30,9 @@ public function rules(): array
             'data.*.field_key' => 'required_with:data|string|max:100',
             'data.*.field_value' => 'nullable|string',
 
+            // HTML 스냅샷
+            'rendered_html' => 'nullable|string',
+
             // 첨부파일
             'attachments' => 'nullable|array',
             'attachments.*.file_id' => 'required_with:attachments|integer|exists:files,id',