refactor: UniversalListPage externalIsLoading 지원 및 스켈레톤 개선

- UniversalListPage에 externalIsLoading prop 추가
- CardTransactionDetailClient DevFill 자동입력 기능 추가
- 여러 컴포넌트 로딩 상태 처리 개선
- skeleton 컴포넌트 확장

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

src/components/process-management/ProcessDetailClientV2.tsx

@@ -13,7 +13,7 @@ import { ProcessDetail } from './ProcessDetail';
 import { ProcessForm } from './ProcessForm';
 import { getProcessById } from './actions';
 import type { Process } from '@/types/process';
-import { ContentLoadingSpinner } from '@/components/ui/loading-spinner';
+import { DetailPageSkeleton } from '@/components/ui/skeleton';
 import { ErrorCard } from '@/components/ui/error-card';
 import { toast } from 'sonner';
 
@@ -87,7 +87,7 @@ export function ProcessDetailClientV2({ processId, initialMode }: ProcessDetailC
 
   // 로딩 중
   if (isLoading) {
-    return <ContentLoadingSpinner text="공정 정보를 불러오는 중..." />;
+    return <DetailPageSkeleton sections={1} fieldsPerSection={4} />;
   }
 
   // 에러 발생 (view/edit 모드에서)