Complete verification links and preserve verified login email (#60)

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

@@ -19,11 +19,13 @@ class DummyVerificationService implements VerificationService, SimulationInfo {
   const DummyVerificationService({
     this.delay = const Duration(milliseconds: 600),
     this.sendFailure,
+    this.verifiedEmail = 'alex@example.com',
   });
   @override
   bool get isSimulated => true;
   final Duration delay;
   final VerificationError? sendFailure;
+  final String verifiedEmail;
 
   @override
   Future<VerificationResult> send({
@@ -41,7 +43,7 @@ class DummyVerificationService implements VerificationService, SimulationInfo {
     switch (token) {
       case 'demo-valid':
         return VerificationMapper.fromDTO(
-          const VerificationDTO(simulated: true),
+          VerificationDTO(simulated: true, email: verifiedEmail),
         );
       case 'demo-expired':
         throw const VerificationException(VerificationError.expired);