added wallet source to quotation preparation

frontend/pshared/lib/models/wallet/asset.dart

@@ -0,0 +1,14 @@
+import 'package:pshared/models/payment/chain_network.dart';
+
+
+class WalletAsset {
+  final ChainNetwork chain;
+  final String tokenSymbol;
+  final String contractAddress;
+
+  const WalletAsset({
+    required this.chain,
+    required this.tokenSymbol,
+    required this.contractAddress,
+  });
+}