Captcha for login and recover password

[Ralkage]

I thought about this recently as well; we'll have a chat internally about possibly complementing both :)

[imorland]

This will become possible to implement when https://github.com/flarum/framework/pull/3670 and https://github.com/flarum/framework/pull/3671 are available

I'll circle back here when it's merged and released!