Fixed compilation

frontend/pshared/lib/data/dto/ledger/balance.dart

@@ -0,0 +1,27 @@
+import 'package:json_annotation/json_annotation.dart';
+
+import 'package:pshared/data/dto/money.dart';
+
+part 'balance.g.dart';
+
+
+@JsonSerializable(
+  includeIfNull: false,   // <- omitempty behavior
+  explicitToJson: true,   // <- nested DTOs call toJson()
+)
+class LedgerBalanceDTO {
+  final String ledgerAccountRef;
+  final MoneyDTO? balance;
+  final int version;
+  final DateTime? lastUpdated;
+
+  const LedgerBalanceDTO({
+    required this.ledgerAccountRef,
+    this.balance,
+    required this.version,
+    this.lastUpdated,
+  });
+
+  factory LedgerBalanceDTO.fromJson(Map<String, dynamic> json) => _$LedgerBalanceDTOFromJson(json);
+  Map<String, dynamic> toJson() => _$LedgerBalanceDTOToJson(this);
+}