core: auto disconnect inactive session

packages/ui-default/pages/record_detail.page.ts

@@ -1,6 +1,7 @@
 import { NamedPage } from 'vj/misc/Page';
 
 const page = new NamedPage('record_detail', async () => {
+  if (!UiContext.socketUrl) return;
   const [{ default: SockJs }, { DiffDOM }] = await Promise.all([
     import('../components/socket'),
     import('diff-dom'),