fix(14-perf): fix scroll jumping and input latency

Root causes addressed:
- track-list had no _itemSize hint for flow layout — virtualizer
  defaulted to 100px, measured actual ~33px rows, then called
  _correctScrollError/scrollTo on every scroll causing visible jumps
- will-change:transform on virtualizer elements caused nested GPU
  layers (virtualizer positions children with transforms internally)
  adding compositor overhead instead of helping
- content-visibility:auto on album cards conflicted with virtualizer's
  own DOM recycling, causing redundant layout recalculation
- track-list visibilityChanged handler wrote to store synchronously
  on every event (per-item during scroll) without any throttling
- IIFE closure in renderTrackRow created a new function per row per render

Fixes applied:
- Add _itemSize:{height:33} + fixed height:33px on .track-row (matches
  queue-panel pattern that already worked smoothly)
- Add overflow-anchor:none on track-list virtualizer
- Remove will-change:transform from all 6 scroll containers
- Remove content-visibility:auto from album cards
- RAF-throttle visibilityChanged scroll position saves
- Replace IIFE with direct cols.map() in template

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

@@ -302,7 +302,6 @@ export class QueuePanel
             flex: 1;
             overflow-y: auto;
             contain: paint;
-            will-change: transform;
             overflow-anchor: none;
         }