The collapse handler waited a fixed itemCount*25+230ms for the
section-domino-out keyframes, but the CSS rule only targeted .list-item.
#models-section uses .models-row, so the rule matched nothing: no
animation played and itemCount was 0, leaving a flat ~230ms pause before
the section snapped shut.
- CSS: the collapse/expand animation rules now match
:is(.list-item, .models-row) so the Models rows actually animate.
- JS: drive the collapse off the real animations via getAnimations()
instead of a hard-coded timeout. Wait only on the section-domino-out
keyframes (ignoring unrelated/infinite animations); collapse
immediately when nothing animates so there is never a dead pause. A
generation token neutralizes stale callbacks from rapid toggles, with
a 600ms safety net so a section can't get stuck open.
