feat(fe): standardize loading UI using shimmer SkeletonLoader across QueryStateBoundary and AGENTS.md

frontend/src/shared/ui/QueryStateBoundary.vue

@@ -1,6 +1,7 @@
 <script setup lang="ts">
 import KsButton from './components/KsButton.vue'
 import KsInlineMessage from './components/KsInlineMessage.vue'
+import SkeletonLoader from './components/SkeletonLoader.vue'
 const props = defineProps<{
   loading: boolean
   processing?: boolean
@@ -16,12 +17,14 @@ const props = defineProps<{
   expired?: boolean
   readonly?: boolean
   correlationId?: string
+  skeletonType?: 'text' | 'card' | 'avatar' | 'table' | 'list'
+  skeletonRows?: number
 }>()
 const emit = defineEmits<{ retry: [] }>()
 </script>
 <template>
   <section class="ks-query-boundary" :aria-busy="props.loading || props.processing">
-    <KsInlineMessage v-if="props.loading" severity="info" message="불러오는 중입니다." />
+    <SkeletonLoader v-if="props.loading" :type="props.skeletonType ?? 'table'" :rows="props.skeletonRows ?? 6" />
     <KsInlineMessage v-else-if="props.unauthorized" severity="warning" title="로그인 필요" message="로그인 후 다시 시도하세요." />
     <KsInlineMessage v-else-if="props.forbidden" severity="danger" title="권한 없음" message="이 작업을 수행할 권한이 없습니다." />
     <KsInlineMessage v-else-if="props.conflict" severity="warning" title="변경 충돌" message="다른 사용자가 먼저 변경했습니다. 최신 버전을 확인하세요." />