更新应用配置，将版本信息中的开发者名称修改为“Marvin Studio”；调整在线大厅和欢迎界面的间距，优化用户界面布局。

lib/config/app_config.dart

@@ -20,6 +20,6 @@ class AppConfig {
   /// UI配置
   static const String appName = '青蛙跳井';
   static const String appVersion =
-      "${String.fromEnvironment('APP_VERSION', defaultValue: 'local-dev')} · 由 AI 驱动开发";
+      "${String.fromEnvironment('APP_VERSION', defaultValue: 'local-dev')} · Marvin Studio";
   static const double pageMaxWidth = 600;
 }

lib/screens/online_lobby_screen.dart

@@ -136,10 +136,10 @@ class _OnlineLobbyScreenState extends ConsumerState<OnlineLobbyScreen>
 
                             // 房间操作
                             _buildCreateRoomSection(),
-                            const SizedBox(height: 10),
+                            const SizedBox(height: 20),
                             _buildJoinRoomSection(),
 
-                            const SizedBox(height: 30),
+                            const SizedBox(height: 20),
                             // 返回按钮
                             _buildBackButton(),
                           ],

lib/screens/welcome_screen.dart

@@ -123,7 +123,7 @@ class WelcomeScreen extends ConsumerWidget {
           context: context,
           ref: ref,
           icon: Icons.smart_toy,
-          title: '🤖 人机对战',
+          title: '人机对战',
           subtitle: '挑战智能AI，测试你的策略',
           color: Colors.blue.shade600,
           onTap: () => _startGame(context, ref, aiMode: true),
@@ -133,7 +133,7 @@ class WelcomeScreen extends ConsumerWidget {
           context: context,
           ref: ref,
           icon: Icons.people,
-          title: '👥 双人对战',
+          title: '双人对战',
           subtitle: '与朋友面对面对决',
           color: Colors.orange.shade600,
           onTap: () => _startGame(context, ref, aiMode: false),
@@ -143,7 +143,7 @@ class WelcomeScreen extends ConsumerWidget {
           context: context,
           ref: ref,
           icon: Icons.wifi,
-          title: '🌐 在线对战',
+          title: '在线对战',
           subtitle: '与全球玩家实时对战',
           color: Colors.purple.shade600,
           onTap: () => _goToOnlineLobby(context),