fix(aihr): label case list demo fallback

frontend/src/views/knowledge/cases.vue

@@ -14,6 +14,15 @@
       </div>
     </section>
 
+    <el-alert
+      v-if="recordsFallback"
+      class="demo-data-alert"
+      title="案例列表接口暂不可用，当前显示演示记录，不代表真实案例库数据"
+      type="warning"
+      :closable="false"
+      show-icon
+    />
+
     <section class="case-grid">
       <article class="panel upload-panel">
         <div class="panel-title">
@@ -180,6 +189,7 @@ const apiTags = ref<CaseTag[]>([]);
 const apiRecord = ref<CaseRecord | null>(null);
 const apiSampleHint = ref('');
 const recordsLoading = ref(false);
+const recordsFallback = ref(false);
 const detailVisible = ref(false);
 const caseDetail = ref<CaseDetailResponse | null>(null);
 const projectExtOrgId = ref('');
@@ -276,8 +286,10 @@ async function loadCaseRecords() {
   try {
     const { data } = await getCaseRecords();
     records.value = data ?? [];
+    recordsFallback.value = false;
   } catch {
     records.value = [...baseRecords];
+    recordsFallback.value = true;
     ElMessage.warning('案例列表接口暂不可用，当前展示演示记录');
   } finally {
     recordsLoading.value = false;