refactor: keep only dashboard sidebars and their state

src/app/dashboard/page.tsx

@@ -1,13 +1,12 @@
 import { Suspense } from "react";
-import { Brand } from "@/components/brand";
 import Dashboard from "./dashboard";
 
 export default function DashboardPage() {
   return (
     <Suspense fallback={
-      <div className="loading-page">
-        <Brand />
-        <p>正在打开你的创作空间…</p>
+      <div className="dashboard sidebar-only" aria-label="正在加载侧边栏" aria-busy="true">
+        <aside className="icon-rail" />
+        <aside className="workspace-sidebar" />
       </div>
     }>
       <Dashboard />

src/styles/globals.css

@@ -2863,3 +2863,13 @@ a.bg-primary {
   font-size: 12px;
   line-height: 1.8;
 }
+
+/* Keep the sidebar-only dashboard accessible at narrow viewport widths. */
+.sidebar-only .workspace-sidebar {
+  display: block;
+  max-width: calc(100vw - 48px);
+}
+.sidebar-only button:disabled {
+  opacity: 0.45;
+  cursor: not-allowed;
+}