Persist language and theme in user settings instead of local storage

What is the problem you are facing?

Each time I reopen funkwhale in my browser, I have to scroll down to change language to French and Dark theme.

My browser is in English and I clean cookies when browser is closed.

I see Funkwhale as an app more than a simple website. Website autodetecting your language is fine, but in an app, I would like it to remember my language and theme as part of my profile when I'm logged in.

What are the possible drawbacks or issues with the requested changes?

Might be less accessible because it might not stay in the footer. It should be in the user profile page. (though footer is not very intuitive IMHO)

Context

Funkwhale 0.20.1

Maybe it will be outdated with the new design (?)