Show accepted signup delivery without a second send step (#62)

frontend/packages/sxchnge_auth/lib/src/services/dummy.dart

@@ -40,8 +40,9 @@ class DummySignupService implements SignupService, SimulationInfo {
   Future<AuthResult> signup(SignupRequest request) async {
     await Future<void>.delayed(delay);
     if (failure case final error?) throw AuthException(error);
-    return AuthMapper.fromDTO(
+    return AuthMapper.signup(
       const AuthDTO(userId: 'demo-user', simulated: true),
+      email: request.email.trim(),
     );
   }
 }