fix(player): 修复清晰度切换闪屏与还原黑屏

lib/pages/player/widgets/player_overlay.dart

@@ -158,16 +158,20 @@ class PlayerPlaybackOverlay extends StatelessWidget {
   }
 
   Widget _rail(BuildContext context) {
-    final compact = MediaQuery.sizeOf(context).height < 700;
     return Positioned(
       right: AppDimens.spaceMd,
-      top: MediaQuery.sizeOf(context).height * (compact ? 0.30 : 0.43),
+      // 底部锚定：无论屏幕高矮，始终悬在进度条上方，不会压到进度条。
+      bottom: 120,
       child: IgnorePointer(
         ignoring: scrubbing,
         child: Opacity(
           opacity: scrubbing ? 0 : 1,
           child: InteractionRail(
             key: const Key('player-interaction-rail'),
+            itemGap: 12,
+            buttonSize: 48,
+            iconSize: 36,
+            countFontSize: 15,
             items: [
               InteractionRailItem(
                 key: const Key('player-rail-save'),
@@ -336,7 +340,7 @@ class PlayerPlaybackOverlay extends StatelessWidget {
                     color: AppColors.onPrimary,
                     fontFamily: 'Outfit',
                     fontSize: 18,
-                    fontWeight: FontWeight.w800,
+                    fontWeight: FontWeight.w400,
                     shadows: _playerTextShadows,
                   ),
                 ),