feat: refund page

lib/presentation/refund/bloc/refund_event.dart

@@ -0,0 +1,10 @@
+part of 'refund_bloc.dart';
+
+@freezed
+class RefundEvent with _$RefundEvent {
+  const factory RefundEvent.refundPayment({
+    required String paymentId,
+    required String reason,
+    required int refundAmount,
+  }) = _RefundPayment;
+}