Phase 3.5: Implemented adaptive navigation (BottomBar/Rail) and My Stream console

frontend/lib/main.dart

@@ -1,13 +1,12 @@
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
-import 'package:fvp/fvp.dart' as fvp; // 使用 as fvp 别名
+import 'package:fvp/fvp.dart' as fvp;
 import 'providers/auth_provider.dart';
 import 'providers/settings_provider.dart';
 import 'pages/home_page.dart';
 import 'pages/login_page.dart';
 
 void main() {
-  // 初始化播放器引擎
   fvp.registerWith();
   
   runApp(
@@ -28,10 +27,22 @@ class HightubeApp extends StatelessWidget {
 
     return MaterialApp(
       title: 'Hightube',
+      // 设置深色主题为主，更符合视频类应用的审美
       theme: ThemeData(
-        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
         useMaterial3: true,
+        colorScheme: ColorScheme.fromSeed(
+          seedColor: Colors.deepPurple,
+          brightness: Brightness.light,
+        ),
       ),
+      darkTheme: ThemeData(
+        useMaterial3: true,
+        colorScheme: ColorScheme.fromSeed(
+          seedColor: Colors.deepPurple,
+          brightness: Brightness.dark,
+        ),
+      ),
+      themeMode: ThemeMode.system, // 跟随系统切换深浅色
       home: auth.isAuthenticated ? HomePage() : LoginPage(),
       debugShowCheckedModeBanner: false,
     );