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/StaffManage.vue

@@ -88,8 +88,8 @@ async function loadRoles() {
   roles.value = (data.data ?? []) as RoleOption[];
 }
 
-async function load() {
-  loading.value = true;
+async function load(opts?: { silent?: boolean }) {
+  if (!opts?.silent) loading.value = true;
   try {
     const { data } = await api.get('/admin/staff', {
       params: {
@@ -104,7 +104,7 @@ async function load() {
     rows.value = [];
     total.value = 0;
   } finally {
-    loading.value = false;
+    if (!opts?.silent) loading.value = false;
   }
 }
 
@@ -251,8 +251,9 @@ onMounted(async () => {
   await loadRoles();
   await load();
 });
-// KeepAlive 激活时静默刷新
-onActivated(() => { if (rows.value.length > 0) void load(); });
+onActivated(() => {
+  if (rows.value.length > 0) void load({ silent: true });
+});
 </script>
 
 <template>