fix(ui): 拆分媒体骨架底色，恢复可见度

lib/pages/drama_detail/widgets/drama_episode_states.dart

@@ -13,7 +13,7 @@ const double _gridSpacing = 8;
 const double _radius = 10;
 const double _horizontal = 14;
 const double _sectionTop = 16;
-const double _minOpacity = 0.65;
+const double _minOpacity = 0.45;
 const double _maxOpacity = 0.8;
 const Duration _breathDuration = Duration(milliseconds: 900);
 
@@ -94,7 +94,7 @@ class _DramaEpisodesLoadingState extends State<DramaEpisodesLoading>
               opacity: _opacity,
               child: Container(
                 decoration: BoxDecoration(
-                  color: AppColors.skeletonSurface,
+                  color: AppColors.skeletonMedia,
                   borderRadius: BorderRadius.circular(_radius),
                 ),
               ),

lib/pages/recommend/recommend_page.dart

@@ -426,7 +426,7 @@ class _RecommendFeedSkeleton extends StatelessWidget {
               height: 176,
               child: DecoratedBox(
                 decoration: BoxDecoration(
-                  color: AppColors.skeletonSurface,
+                  color: AppColors.skeletonMedia,
                   borderRadius: BorderRadius.all(Radius.circular(12)),
                 ),
               ),
@@ -465,7 +465,7 @@ class _SkeletonLine extends StatelessWidget {
       width: width,
       height: height,
       decoration: BoxDecoration(
-        color: AppColors.skeletonSurface,
+        color: AppColors.skeletonMedia,
         borderRadius: BorderRadius.circular(6),
       ),
     );