fetchUserOffer method
Fetches the server-resolved offer for the currently-identified user.
Returns the raw UserOfferResponse wire map. The facade converts this
to UserOfferResponse.
Implementation
@override
Future<Map<String, dynamic>> fetchUserOffer() async {
final result = await methodChannel.invokeMethod<Map>('fetchUserOffer');
return Map<String, dynamic>.from(result!);
}