perf(admin): 实现切页即时导航与列表 loading 壳

非阻塞 session 刷新、侧边栏 chunk 预取、KeepAlive 对齐，以及按 tab 延迟加载重型列表页。

apps/admin/src/views/Contents.vue

@@ -1,5 +1,7 @@
 <script setup lang="ts">
-import { ref, computed, watch } from 'vue';
+defineOptions({ name: 'AdminContents' });
+
+import { ref, computed, watch, onActivated } from 'vue';
 import { ElMessage, ElMessageBox } from 'element-plus';
 import type { TableInstance } from 'element-plus';
 import { useAdminLocale } from '../composables/useAdminLocale';
@@ -237,6 +239,11 @@ watch([activeType, filterStatus], () => {
   void load();
 });
 
+onActivated(() => {
+  if (activeType.value === 'INBOX_NOTIFY') return;
+  if (items.value.length > 0) void load();
+});
+
 function onSelectionChange(rows: ContentItem[]) {
   selectedRows.value = rows;
 }