implemented backend wallet service connection

frontend/pshared/lib/api/responses/wallet_balance.dart

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+import 'package:json_annotation/json_annotation.dart';
+
+import 'package:pshared/data/dto/wallet/balance.dart';
+
+part 'wallet_balance.g.dart';
+
+
+@JsonSerializable(explicitToJson: true)
+class WalletBalanceResponse {
+  final WalletBalanceDTO balance;
+
+  const WalletBalanceResponse({required this.balance});
+
+  factory WalletBalanceResponse.fromJson(Map<String, dynamic> json) => _$WalletBalanceResponseFromJson(json);
+  Map<String, dynamic> toJson() => _$WalletBalanceResponseToJson(this);
+}

frontend/pshared/lib/api/responses/wallets.dart

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+import 'package:json_annotation/json_annotation.dart';
+
+import 'package:pshared/data/dto/wallet/wallet.dart';
+
+part 'wallets.g.dart';
+
+
+@JsonSerializable(explicitToJson: true)
+class WalletsResponse {
+  final List<WalletDTO> wallets;
+
+  const WalletsResponse({required this.wallets});
+
+  factory WalletsResponse.fromJson(Map<String, dynamic> json) => _$WalletsResponseFromJson(json);
+  Map<String, dynamic> toJson() => _$WalletsResponseToJson(this);
+}