fix(flutter): 简介灰字统一并透明暂停按钮

lib/pages/player/widgets/player_center_toggle.dart

@@ -22,13 +22,9 @@ class PlayerCenterToggle extends StatelessWidget {
       label: playing ? 'Pause' : 'Play',
       child: GestureDetector(
         onTap: onTap,
-        child: Container(
+        child: SizedBox(
           width: 52,
           height: 52,
-          decoration: const BoxDecoration(
-            color: AppColors.blue,
-            shape: BoxShape.circle,
-          ),
           child: Icon(
             playing ? Icons.pause_rounded : Icons.play_arrow_rounded,
             color: AppColors.onPrimary,

lib/pages/player/widgets/player_overlay_parts.dart

@@ -241,16 +241,11 @@ class _EpisodeSynopsis extends StatefulWidget {
 class _EpisodeSynopsisState extends State<_EpisodeSynopsis> {
   bool _expanded = false;
 
-  static const TextStyle _labelStyle = TextStyle(
-    color: AppColors.onPrimary,
-    fontSize: 12,
-    fontWeight: FontWeight.w700,
-    shadows: _playerTextShadows,
-  );
-
-  static const TextStyle _synopsisStyle = TextStyle(
+  /// 「第 n 集」、分隔符与简介正文共用同一套灰字规格。
+  static const TextStyle _lineStyle = TextStyle(
     color: AppColors.playerMuted,
     fontSize: 12,
+    fontWeight: FontWeight.w500,
     height: 1.35,
     shadows: _playerTextShadows,
   );
@@ -270,17 +265,15 @@ class _EpisodeSynopsisState extends State<_EpisodeSynopsis> {
               key: const Key('player-episode-label'),
               maxLines: 1,
               overflow: TextOverflow.ellipsis,
-              style: _labelStyle,
+              style: _lineStyle,
             ),
-            const Padding(
-              padding: EdgeInsets.symmetric(horizontal: 6),
+            Padding(
+              padding: const EdgeInsets.symmetric(horizontal: 6),
               child: Text(
                 '|',
                 maxLines: 1,
-                style: TextStyle(
-                  color: Colors.white54,
-                  fontSize: 12,
-                  shadows: _playerTextShadows,
+                style: _lineStyle.copyWith(
+                  color: AppColors.playerMuted.withValues(alpha: 0.6),
                 ),
               ),
             ),
@@ -290,7 +283,7 @@ class _EpisodeSynopsisState extends State<_EpisodeSynopsis> {
                 key: const Key('player-synopsis'),
                 maxLines: _expanded ? null : 1,
                 overflow: _expanded ? TextOverflow.clip : TextOverflow.ellipsis,
-                style: _synopsisStyle,
+                style: _lineStyle,
               ),
             ),
             if (!_expanded) _toggle(widget.l10n.expandSynopsis),