The Timeline's comp tabs had a × on the shown comp only, so closing another
comp meant showing it first. A comp tab the Timeline does not show now shows
its × while the pointer is over it, and clicking it closes that comp without
showing it. Every comp tab keeps the ×'s room, so a tab keeps its width when
it is shown or hovered. Automation: `panel.tab.Timeline.<comp>.close` for
each comp's ×; `panel.tab.Timeline.close` stays for the shown comp's.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
