Add optional KYC flow and service-backed account limits

frontend/app/lib/auth/form.dart

@@ -310,6 +310,10 @@ class _AuthFormState extends State<AuthForm> {
           AuthFeedback(state: state, signUp: _signUp),
         ],
         const SizedBox(height: 20),
+        TextButton(
+          onPressed: () => context.goNamed(AppRoutes.identity),
+          child: Text(l.kycPreview),
+        ),
         Wrap(
           alignment: WrapAlignment.center,
           crossAxisAlignment: WrapCrossAlignment.center,