feat(recommend): 对齐沉浸式推荐页视觉布局

lib/core/theme/app_colors.dart

@@ -23,10 +23,12 @@ abstract final class AppColors {
   static const overlayBar = Color(0x4D000000);
   static const overlayMedium = Color(0x99000000);
   static const headerScrim = Color(0x59000000);
+  static const overlaySecondary = Color(0xFFC7C7CC);
 
   /// 主操作、选中态、播放进度（品牌橙）。
   static const blue = Color(0xFFFF6B2C);
   static const primary = blue;
+  static const actionRed = Color(0xFFFF3B30);
 
   /// 主操作按下态。
   static const bluePressed = Color(0xFFE55A1F);