feat：增加首页登录页面

frontend/src/App.tsx

@@ -11,7 +11,7 @@ import { ChatPanel } from "./components/ChatPanel";
 import { ConfigPanel } from "./components/ConfigPanel";
 import { SessionSidebar } from "./components/SessionSidebar";
 import { ToastContainer } from "./components/Toast";
-import { AuthPage } from "./components/AuthPage";
+import { LandingPage } from "./components/LandingPage";
 import { AuthProvider, useAuth } from "./lib/auth";
 import { loadConfig, loadTheme, saveTheme } from "./lib/storage";
 import { I18nContext, parseLocale, t } from "./lib/i18n";
@@ -232,7 +232,7 @@ function AppContent() {
   }
 
   if (!isAuthenticated) {
-    return <AuthPage />;
+    return <LandingPage />;
   }
 
   return (