style(theme): 客户端切换深色视觉风格

lib/pages/player/widgets/exit_clear_screen_button.dart

@@ -2,6 +2,8 @@
 
 import 'package:flutter/material.dart';
 
+import '../../../core/theme/app_colors.dart';
+
 /// Shared floating action used to leave clear-screen mode.
 class ExitClearScreenButton extends StatelessWidget {
   const ExitClearScreenButton({
@@ -23,8 +25,8 @@ class ExitClearScreenButton extends StatelessWidget {
         onPressed: onPressed,
         padding: EdgeInsets.zero,
         style: IconButton.styleFrom(
-          backgroundColor: const Color(0x80000000),
-          foregroundColor: Colors.white,
+          backgroundColor: AppColors.controlScrim,
+          foregroundColor: AppColors.onPrimary,
           shape: const CircleBorder(),
         ),
         icon: const Icon(Icons.fullscreen_exit_rounded, size: 18),