OnScrollThresholdReachedEventTrigger

Fires on LazyColumn/LazyRow when the scroll position comes within scrollThreshold items of the end of the list — the infinite-scroll pagination signal, guarded by Int.ThresholdReachedEffect so it doesn't re-fire until the list actually grows past its last fired count — or, after a failed page shrinks the list back down, past whatever smaller count it shrank to.