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/pages/Artists.tsx

@@ -126,7 +126,7 @@ export default function Artists() {
 
   const artistGridScrollMargin = useVirtualizerScrollMargin(
     artistGridMeasureRef,
-    () => document.getElementById(APP_MAIN_SCROLL_VIEWPORT_ID),
+    getInpageScrollElement,
     {
       active: !perfFlags.disableMainstageVirtualLists && viewMode === 'grid',
       deps: [artistVirtualRowCount, artistGridCols],
@@ -159,7 +159,7 @@ export default function Artists() {
   const artistListWrapRef = useRef<HTMLDivElement>(null);
   const artistListScrollMargin = useVirtualizerScrollMargin(
     artistListWrapRef,
-    () => document.getElementById(APP_MAIN_SCROLL_VIEWPORT_ID),
+    getInpageScrollElement,
     {
       active: !perfFlags.disableMainstageVirtualLists && viewMode === 'list',
       deps: [artistListFlatRows.length],

src/pages/Composers.tsx

@@ -215,7 +215,7 @@ export default function Composers() {
   const composerListWrapRef = useRef<HTMLDivElement>(null);
   const composerListScrollMargin = useVirtualizerScrollMargin(
     composerListWrapRef,
-    () => document.getElementById(APP_MAIN_SCROLL_VIEWPORT_ID),
+    getInpageScrollElement,
     {
       active: !perfFlags.disableMainstageVirtualLists && viewMode === 'list',
       deps: [composerListFlatRows.length],