fix(flutter): 放大播放图标并加半透明底

lib/pages/player/widgets/player_center_toggle.dart

@@ -4,8 +4,9 @@ import 'package:flutter/material.dart';
 
 import '../../../core/theme/app_colors.dart';
 
-const double _toggleSize = 72;
-const double _iconSize = 40;
+const double _toggleSize = 84;
+const double _iconSize = 48;
+const Color _toggleBackground = Colors.black26;
 const List<Shadow> _iconShadows = [
   Shadow(color: Colors.black54, blurRadius: 12),
 ];
@@ -28,9 +29,13 @@ class PlayerCenterToggle extends StatelessWidget {
       label: playing ? 'Pause' : 'Play',
       child: GestureDetector(
         onTap: onTap,
-        child: SizedBox(
+        child: Container(
           width: _toggleSize,
           height: _toggleSize,
+          decoration: const BoxDecoration(
+            color: _toggleBackground,
+            shape: BoxShape.circle,
+          ),
           child: Icon(
             playing ? Icons.pause_rounded : Icons.play_arrow_rounded,
             color: AppColors.onPrimary,