style: 统一下拉与加载指示器

lib/core/theme/app_colors.dart

@@ -187,6 +187,7 @@ abstract final class AppColors {
 
   /// 播放器控件胶囊与圆形底色。
   static const playerOverlayPill = Color(0xB3000000);
+  static const refreshIndicatorSurface = Color(0x99000000);
   static const cardBottomScrimStart = Color(0x00000000);
   static const cardBottomScrimEnd = Color(0x40000000);
 

lib/core/theme/app_dimens.dart

@@ -53,6 +53,11 @@ abstract final class AppDimens {
   static const double progressHeight = 3;
   static const double progressRadius = 2;
   static const double progressLineHeight = 3;
+  static const double refreshIndicatorSize = 40;
+  static const double refreshIndicatorRadius = 20;
+  static const double refreshSpinnerSize = 20;
+  static const double refreshSpinnerStroke = 2;
+  static const double loadMoreIndicatorHeight = 40;
 
   static const double searchHeight = 40;
   static const double searchRadius = 8;