The document-level click handler in SortDropdown.js called trigger.focus()
unconditionally on every click outside the sort group. When a model card
was clicked to open the modal, focus() triggered scrollIntoView on the
.sort-trigger button, perturbing .page-content.scrollTop and causing the
card grid to jump up a few pixels.
The same interference also broke the back-to-top smooth-scroll animation:
frame-by-frame focus/scroll perturbations caused VirtualScroller to
schedule repeated re-renders, interrupting the compositor-thread scroll.
Fix: only return focus to the trigger when the dropdown was actually open,
so ordinary page clicks (e.g. clicking a model card) never force focus.
