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/items/ItemMasterDataManagement/dialogs/ImportFieldDialog.tsx

@@ -16,7 +16,7 @@ import { Badge } from '@/components/ui/badge';
 import { Input } from '@/components/ui/input';
 import { Label } from '@/components/ui/label';
 import { FormInput, Search, Info, Loader2, Hash, Calendar, CheckSquare, ChevronDown, Type, AlignLeft, Database } from 'lucide-react';
-import { ContentLoadingSpinner } from '@/components/ui/loading-spinner';
+import { ContentSkeleton } from '@/components/ui/skeleton';
 import type { ItemField, ItemMasterField } from '@/contexts/ItemMasterContext';
 import type { FieldUsageResponse } from '@/types/item-master-api';
 import { isNextRedirectError } from '@/lib/utils/redirect-error';
@@ -157,7 +157,7 @@ export function ImportFieldDialog({
 
         <div className="space-y-4">
           {isLoading ? (
-            <ContentLoadingSpinner text="필드 목록을 불러오는 중..." />
+            <ContentSkeleton type="list" rows={5} />
           ) : filteredFields.length === 0 ? (
             <div className="text-center py-8">
               <FormInput className="h-12 w-12 mx-auto text-muted-foreground mb-4" />

src/components/items/ItemMasterDataManagement/dialogs/ImportSectionDialog.tsx

@@ -7,7 +7,7 @@ import { Badge } from '@/components/ui/badge';
 import { Input } from '@/components/ui/input';
 import { Label } from '@/components/ui/label';
 import { Package, Folder, Search, Info, Loader2 } from 'lucide-react';
-import { ContentLoadingSpinner } from '@/components/ui/loading-spinner';
+import { ContentSkeleton } from '@/components/ui/skeleton';
 import type { ItemSection } from '@/contexts/ItemMasterContext';
 import type { SectionUsageResponse } from '@/types/item-master-api';
 import { isNextRedirectError } from '@/lib/utils/redirect-error';
@@ -109,7 +109,7 @@ export function ImportSectionDialog({
 
         <div className="space-y-4">
           {isLoading ? (
-            <ContentLoadingSpinner text="섹션 목록을 불러오는 중..." />
+            <ContentSkeleton type="list" rows={5} />
           ) : filteredSections.length === 0 ? (
             <div className="text-center py-8">
               <Folder className="h-12 w-12 mx-auto text-muted-foreground mb-4" />