intent reference generation + propagation

frontend/pshared/lib/data/dto/payment/payment_quote.dart

@@ -9,11 +9,18 @@ part 'payment_quote.g.dart';
 @JsonSerializable()
 class PaymentQuoteDTO {
   final String? quoteRef;
+  final String? intentRef;
   final QuoteAmountsDTO? amounts;
   final QuoteFeesDTO? fees;
   final FxQuoteDTO? fxQuote;
 
-  const PaymentQuoteDTO({this.quoteRef, this.amounts, this.fees, this.fxQuote});
+  const PaymentQuoteDTO({
+    this.quoteRef,
+    this.intentRef,
+    this.amounts,
+    this.fees,
+    this.fxQuote,
+  });
 
   factory PaymentQuoteDTO.fromJson(Map<String, dynamic> json) =>
       _$PaymentQuoteDTOFromJson(json);

frontend/pshared/lib/data/mapper/payment/quote.dart

@@ -7,6 +7,7 @@ import 'package:pshared/models/payment/quote/quote.dart';
 extension PaymentQuoteDTOMapper on PaymentQuoteDTO {
   PaymentQuote toDomain({String? idempotencyKey}) => PaymentQuote(
     quoteRef: quoteRef,
+    intentRef: intentRef,
     idempotencyKey: idempotencyKey,
     amounts: amounts?.toDomain(),
     fees: fees?.toDomain(),
@@ -17,6 +18,7 @@ extension PaymentQuoteDTOMapper on PaymentQuoteDTO {
 extension PaymentQuoteMapper on PaymentQuote {
   PaymentQuoteDTO toDTO() => PaymentQuoteDTO(
     quoteRef: quoteRef,
+    intentRef: intentRef,
     amounts: amounts?.toDTO(),
     fees: fees?.toDTO(),
     fxQuote: fxQuote?.toDTO(),