feature: add force username option

[javalsai]

Discussed in #119

^{Originally posted by **beatreichenbach** February 25, 2026}

Hello,

Is it possible to force the username instead of the display name?

I can make an option.

Is it possible to force the username field to be always empty?

I'm not sure about this one, might be messy to implement but I'll consider it.

Thank you :)