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/settings/LeavePolicyManagement/index.tsx

@@ -5,7 +5,7 @@ import { PageLayout } from '@/components/organisms/PageLayout';
 import { PageHeader } from '@/components/organisms/PageHeader';
 import { CalendarDays, Loader2 } from 'lucide-react';
 import { Button } from '@/components/ui/button';
-import { ContentLoadingSpinner } from '@/components/ui/loading-spinner';
+import { ContentSkeleton } from '@/components/ui/skeleton';
 import { Label } from '@/components/ui/label';
 import { Input } from '@/components/ui/input';
 import { QuantityInput } from '@/components/ui/quantity-input';
@@ -92,7 +92,7 @@ export function LeavePolicyManagement() {
           description="휴가 정책을 관리합니다"
           icon={CalendarDays}
         />
-        <ContentLoadingSpinner text="휴가 정책을 불러오는 중..." />
+        <ContentSkeleton type="form" rows={6} />
       </PageLayout>
     );
   }