Describe the bug
Token refresh flow doesn't refresh the token, but simply runs the normal auth flow again from the start.

To Reproduce
Steps to reproduce the behavior:

1. Authenticate using either "Guided OAuth Flow" or "Quick OAuth Flow"
2. Then request token refresh either using "Guided Token Refresh" or "Quick Refresh".

Expected behavior

• Not to have a Client Registration step, since token refresh should use the existing client id.
• Use auth server's token refresh functionality, instead of registration/authentication flow. Especially, grant_type should be refresh_token.

Logs
Initiating token refresh clearly shows

grant_type=authorization_code

in the POST request's form data. Instead it should be grant_type=refresh_token

Additional context
Related to #608, but the difference is that there it is about not refreshing the token after a timeout, but here it is about the manual "Guided Token Refresh"/"Quick Refresh" flow.