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/track-list/track-list.ts

@@ -722,6 +722,7 @@ export class TrackList extends LitElement implements SelectionHost, ContextMenuH
       display: flex;
       flex-direction: column;
       overflow: hidden;
+      contain: layout style;
     }
 
     .table-container {
@@ -931,6 +932,8 @@ export class TrackList extends LitElement implements SelectionHost, ContextMenuH
       overflow-x: hidden;
       overflow-y: auto;
       user-select: none;
+      contain: paint;
+      will-change: transform;
     }
 
     .track-row {