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/utils/route-prefetch.ts

@@ -0,0 +1,25 @@
+import type { Router } from 'vue-router';
+
+const prefetchedPaths = new Set<string>();
+
+/** 预取目标路径上所有 lazy route 的 JS chunk（侧边栏 hover/focus 时调用）。 */
+export function prefetchRouteChunks(router: Router, path: string) {
+  const key = path.split('?')[0] || '/';
+  if (prefetchedPaths.has(key)) return;
+
+  let matched = false;
+  try {
+    const resolved = router.resolve(path);
+    for (const record of resolved.matched) {
+      const loader = record.components?.default;
+      if (typeof loader === 'function') {
+        matched = true;
+        void (loader as () => Promise<unknown>)();
+      }
+    }
+  } catch {
+    return;
+  }
+
+  if (matched) prefetchedPaths.add(key);
+}