update theme

lib/features/loyalty/presentation/widgets/points_balance_card.dart

@@ -22,6 +22,7 @@ class PointsBalanceCard extends ConsumerWidget {
 
   @override
   Widget build(BuildContext context, WidgetRef ref) {
+    // Note: This widget uses brand colors (gradient) that don't change with theme
     final pointsState = ref.watch(loyaltyPointsProvider);
     final numberFormat = NumberFormat('#,###', 'vi_VN');
     final dateFormat = DateFormat('dd/MM/yyyy', 'vi_VN');