Add backup codes generation

[vegaelle]

Hi. I’m testing this app, and I’m quite happy that it exists. Code generation, and actual 2FA login works for me, however I can’t seem to find the possibility for an user to generate one-time backup codes. Without those, account recovery can be quite painful. Generating a few one-time codes, and asking the user to store them securely, is a well-used recovery method, and I suggest it could be implemented in this project.

On the other side, the app enables to add multiple TOTP devices, which is very good, and enables account recovery through another device if the first one is lost/broken/compromised. However, I’d like to use something like an offline KeepassXC database to store the second token, but I can’t add a TOTP code by scanning, and must enter the secret directly. So I’m opening a second issue for this (#19).

[Sreini]

Also looking for this feature. Generating a one time recovery code is sorely needed.