A SignedPreKey should only be generated once at install time
A SignedPreKey rotation can be implemented at a later point.
To generate a new SignedPreKey for every publish is overkill
and there is missing a deletion mechansim for old, not used,
SignedPreKeys, which is a potential security risk.

additionally small refactoring of UI code

Previously only the "Sign In" event prompted publishing our Data
to the Node. Normally at plugin installation you are already
signed in, so the event doesnt get triggered

The icon can not be recognized. So I used a cropped part of the image.