perf(14-01): add GPU promotion and containment to all scroll containers

- contain: layout style on :host of all 6 scroll-heavy components
- contain: paint + will-change: transform on all scroll containers for GPU compositing
- content-visibility: auto + contain-intrinsic-size on .album-card for off-screen skip
- cover-grid, track-list, queue-panel, artists-view, genres-view, playlist-view

frontend/src/components/queue-panel/queue-panel.ts

@@ -211,6 +211,7 @@ export class QueuePanel
             background-color: var(--yj-bg-surface, #212529);
             display: flex;
             flex-direction: row;
+            contain: layout style paint;
         }
 
         :host([open]) {
@@ -300,6 +301,8 @@ export class QueuePanel
         lit-virtualizer {
             flex: 1;
             overflow-y: auto;
+            contain: paint;
+            will-change: transform;
         }
 
         .track-item {