fix(flutter): 放大透明播放按钮

lib/pages/player/widgets/player_center_toggle.dart

@@ -4,6 +4,12 @@ import 'package:flutter/material.dart';
 
 import '../../../core/theme/app_colors.dart';
 
+const double _toggleSize = 72;
+const double _iconSize = 40;
+const List<Shadow> _iconShadows = [
+  Shadow(color: Colors.black54, blurRadius: 12),
+];
+
 /// 首页沉浸流与全屏播放器共用的播放/暂停按钮。
 class PlayerCenterToggle extends StatelessWidget {
   const PlayerCenterToggle({
@@ -23,12 +29,13 @@ class PlayerCenterToggle extends StatelessWidget {
       child: GestureDetector(
         onTap: onTap,
         child: SizedBox(
-          width: 52,
-          height: 52,
+          width: _toggleSize,
+          height: _toggleSize,
           child: Icon(
             playing ? Icons.pause_rounded : Icons.play_arrow_rounded,
             color: AppColors.onPrimary,
-            size: 26,
+            size: _iconSize,
+            shadows: _iconShadows,
           ),
         ),
       ),