[Feature]: Make user avatar hoverable

[Slartibartfass2]

To which use case does your feature request relate?

No response

Is your feature request related to a problem? Please describe

Currently, the user avatar only shows the initials and for the navigation bar that's fine.
However, e.g. in the paper list entry, when review decisions are shown with their respective user avatar, the user might wonder, to whom the initials belong to. If there are two project members with the same initials, they should be distinguishable.

Describe the solution you'd like

I propose showing the user's full name in a tooltip while hovering.

Describe alternatives you've considered

No response

Anything else?

No response