fix(ui): 保留空态既有字号口径

lib/core/theme/app_dimens.dart

@@ -17,6 +17,8 @@ abstract final class AppDimens {
   static const double pillRadius = 20;
 
   static const double caption = 12;
+  static const double emptyStateSubtitle = 12.5;
+  static const double emptyStateAction = 13;
   static const double body = 14;
   static const double listTitle = 15;
   static const double sectionTitle = 16;