style(appShell): 优化应用外壳及底部导航样式与结构

- 在 tailwind 配置中添加应用外壳相关的 safelist 类名
- 替换 App.tsx 中应用外壳容器的类名，去除多余的内边距容器
- 在现代和遗留样式文件中新增移动端全屏、桌面居中列的样式规则
- 新增底部导航外层和内层的样式及响应式布局支持
- appShell.ts 中将样式类改为统一的 x8- 前缀类名
- BottomNav 组件使用新的样式类名以匹配样式调整
- Home 页面 ListRow 组件支持可选缩略图展示，增加界面展示丰富度

client/src/App.tsx

@@ -22,7 +22,7 @@ import SelectPage from "./pages/SelectPage";
 import CommunityPage from "./pages/CommunityPage";
 import { AIDrawerProvider } from "./contexts/AIDrawerContext";
 import DesktopAIShell from "./components/DesktopAIShell";
-import { appShellColumnClass, appShellGutterClass } from "./lib/appShell";
+import { appShellColumnClass, appShellOuterClass } from "./lib/appShell";
 
 const EQPage = lazy(() => import("./pages/EQPage"));
 const AIPage = lazy(() => import("./pages/AIPage"));
@@ -75,10 +75,8 @@ function App() {
             <Toaster />
             <Router hook={useHashLocation}>
               <AIDrawerProvider>
-                <div
-                  className={`min-h-dvh bg-[#0d1117] flex justify-center ${appShellGutterClass}`}
-                >
-                  <div className={`min-h-dvh ${appShellColumnClass}`}>
+                <div className={appShellOuterClass}>
+                  <div className={appShellColumnClass}>
                     <DesktopAIShell>
                       <AppRouter />
                     </DesktopAIShell>