My server can now process preferredUsername changes. I also changed everything to use actor ID as a primary identifier. Previously, actor ID was a secondary identifier after the webfinger address (Mastodon style) - this is a pretty big change and I hope I didn't break anything. Webfinger is now optional (but preferredUsername is still required).

In UI accounts without webfinger address will have actor ID in its place.

https://codeberg.org/fediverse/fep/src/branch/main/fep/03c1/fep-03c1.md