When creating a new user, omit group_ids from the request body if the
admin never touched the selector AND the groups query hasn't successfully
resolved (still loading or errored). This lets the backend's
default-group provisioning apply rather than receiving an empty array
and producing a locked-out zero-group user. When groups have loaded and
the preselection is untouched, the explicit selection is still sent.
The Groups tab now shows skeleton rows while loading and a muted notice
on error instead of a silent empty selector.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>