fix(flutter): 修复详情与播放器底部闪白

lib/core/theme/app_theme.dart

@@ -107,6 +107,11 @@ abstract final class AppTheme {
           side: BorderSide(color: AppColors.border),
         ),
       ),
+      bottomSheetTheme: const BottomSheetThemeData(
+        backgroundColor: Colors.transparent,
+        modalBackgroundColor: Colors.transparent,
+        surfaceTintColor: Colors.transparent,
+      ),
       switchTheme: SwitchThemeData(
         thumbColor: WidgetStateProperty.resolveWith(
           (states) => states.contains(WidgetState.selected)