Passkey login button #41

currently you need to type your username for you to be able to pick a passkey, but passkeys do not actually require usernames to be usable. see sign in with passkey on github (https://github.com/login). honestly it's been a while since i've seen how passkeys work but like there's a mode that just shows all passkeys for the site and let's you pick from that on your passkey ui instead of the browser

it would make it a lot nicer to login on webui itself and slightly better to login from other apps for as long as you login with the pds url

maybe also make it automatically call the passkey interface when you login with an actual username and that user has the passkey login