unified gateway interfaces

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

@@ -20,6 +20,9 @@ class PaymentIntentDTO {
   @JsonKey(name: 'settlement_mode')
   final String? settlementMode;
 
+  @JsonKey(name: 'settlement_currency')
+  final String? settlementCurrency;
+
   final Map<String, String>? attributes;
   final CustomerDTO? customer;
 
@@ -30,6 +33,7 @@ class PaymentIntentDTO {
     this.amount,
     this.fx,
     this.settlementMode,
+    this.settlementCurrency,
     this.attributes,
     this.customer,
   });