fix(ui): stable shelf-card menu triggers, a named Button by type, true layout comments

- Home's rail handed each card a fresh `() => menu.triggerProps(c)` per
  render, defeating memo(VideoCard) on every tile whenever the menu's own
  state changed. `useItemTriggers` (ui/useContextMenu) keeps one trigger per
  item, index-aligned; tested for identity across renders.
- The Button accessible-name union had one hole: `<Button icon={…} />` with
  no children and no size typechecked into a nameless button. A textful
  button now needs children or a name; pinned with @ts-expect-error.
- comfortPin's header said the pin belongs "on every card and row", which
  the code never meant (an episode, a season, a person are not pin kinds).
  It now says what is pinnable — and the show page's Related strip, whose
  shows ARE pinnable, gets the pin menu it was missing (and a rem width).
- gridColumns / feedView / VirtualGrid claimed layouts 1024–2560 are
  "byte-identical" under the column cap; the small cards are capped at 2560
  with the filter rail collapsed. The comments say so.

frontend/src/components/plexViews.tsx

@@ -312,6 +312,7 @@ export function PlexShowView({
   const [addTarget, setAddTarget] = useState<PlexAddTarget | null>(null);
   const [collOpen, setCollOpen] = useState(false);
   const [busy, setBusy] = useState(false);
+  const relatedPin = useContextMenu<PlexCard>();
 
   const show = d?.show;
   const showLib = show?.library ?? undefined;
@@ -532,10 +533,15 @@ export function PlexShowView({
             <CastStrip cast={show.cast} onFilter={onFilter} onOpenPerson={onOpenPerson} />
           )}
           {d.related.length > 0 && showRelated && (
-            <RelatedStrip related={d.related} onOpen={onOpenShow} />
+            <RelatedStrip
+              related={d.related}
+              onOpen={onOpenShow}
+              menuProps={relatedPin.triggerProps}
+            />
           )}
         </>
       )}
+      <PlexPinMenu menu={relatedPin} />
 
       {addTarget && <PlexPlaylistAdd target={addTarget} onClose={() => setAddTarget(null)} />}
       {collOpen && show && showLib && (