Alt-dragging an artboard moved it like a plain drag. artboard.move now
takes copy: it leaves the artboard (and the art it carries) where it
is and moves a copy, named "<name> copy", with copies of that art. The
Artboard tool previews it while Alt is held, as "Duplicate Artboard"
(Alt pressed or released mid-drag switches between copy and move),
and makes the copy the active artboard, as in the reference app.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>