fix: restore tubco user onboarding access

backend/workflows/forms.py

@@ -131,7 +131,13 @@ class AppLoginForm(forms.Form):
         username = cleaned_data.get('username')
         password = cleaned_data.get('password')
         if username and password:
-            self.user_cache = authenticate(self.request, username=username, password=password)
+            login_value = (username or '').strip()
+            auth_username = login_value
+            user_model = get_user_model()
+            matched_user = user_model.objects.filter(email__iexact=login_value).first()
+            if matched_user:
+                auth_username = matched_user.username
+            self.user_cache = authenticate(self.request, username=auth_username, password=password)
             if self.user_cache is None:
                 raise ValidationError(self.error_messages['invalid_login'], code='invalid_login')
             if not self.user_cache.is_active: