fix(ui): in-page browse virtual lists and cover load priority (#783)

* fix(ui): in-page browse virtual lists and cover load priority

Align virtualizer scrollMargin with the in-page scroll viewport so
artist/album rows do not vanish on deep scroll after #731. Resolve
CachedImage IntersectionObserver root to the nearest scrolling pane so
network fetch slots favor visible covers; throttle Artists infinite scroll
to one page per visibleCount update.

* chore(release): CHANGELOG and credits for PR #783

src/hooks/useArtistsInfiniteScroll.ts

@@ -40,16 +40,23 @@ export function useArtistsInfiniteScroll({
   const [loadingMore, setLoadingMore] = useState(false);
   const loadMoreRef = useRef<() => void>(() => {});
   const observerInst = useRef<IntersectionObserver | null>(null);
+  /** Blocks overlapping sentinel callbacks until `visibleCount` commits. */
+  const loadPendingRef = useRef(false);
 
   const loadMore = useCallback(() => {
-    if (loadingMore) return;
+    if (loadPendingRef.current) return;
+    loadPendingRef.current = true;
     setLoadingMore(true);
     setVisibleCount(prev => prev + pageSize);
-    setTimeout(() => setLoadingMore(false), 100);
-  }, [loadingMore, pageSize]);
+  }, [pageSize]);
 
   loadMoreRef.current = loadMore;
 
+  useEffect(() => {
+    loadPendingRef.current = false;
+    setLoadingMore(false);
+  }, [visibleCount]);
+
   useEffect(() => {
     setVisibleCount(pageSize);
     // resetDeps is intentionally spread into the dep array.