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/artists-view/artists-view.ts

@@ -231,7 +231,6 @@ export class ArtistsView
                 overflow-y: auto;
                 overflow-x: hidden;
                 contain: paint;
-                will-change: transform;
             }
 
             lit-virtualizer {

frontend/src/components/cover-grid/cover-grid-styles.ts

@@ -131,7 +131,6 @@ const gridStyles = css`
         position: relative;
         overflow-y: auto;
         contain: paint;
-        will-change: transform;
     }
 
     /* ========================================
@@ -149,8 +148,6 @@ const gridStyles = css`
             transform 0.15s ease;
         box-sizing: border-box;
         width: var(--card-width, 176px);
-        content-visibility: auto;
-        contain-intrinsic-size: auto var(--card-width, 176px) auto calc(var(--card-width, 176px) + 40px);
     }
 
     .album-card:hover {

frontend/src/components/genres-view/genres-view.ts

@@ -235,7 +235,6 @@ export class GenresView
             overflow-y: auto;
             overflow-x: hidden;
             contain: paint;
-            will-change: transform;
         }
 
         lit-virtualizer {

frontend/src/components/playlist-view/playlist-view.ts

@@ -308,7 +308,6 @@ export class PlaylistView extends LitElement {
             display: flex;
             flex-direction: column;
             contain: paint;
-            will-change: transform;
         }
 
         .playlist-item {

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;
         }
 

frontend/src/components/track-list/track-list.ts

@@ -195,8 +195,15 @@ export class TrackList extends LitElement implements SelectionHost, ContextMenuH
     private resizeObserver: ResizeObserver | null =
         null;
 
-    private flowLayout = flow();
+    // _itemSize matches the fixed .track-row height (33px) so lit-virtualizer
+    // doesn't need to measure items. Without this hint, the default 100px
+    // estimate causes constant scroll error correction (scrollTo() calls)
+    // that produce visible jumping/skipping during scroll.
+    private flowLayout = flow({
+        _itemSize: { width: 100, height: 33 },
+    } as Parameters<typeof flow>[0]);
     private hasRestoredScroll = false;
+    private scrollSaveRAFId: number | null = null;
 
     // =================================================================
     // Filtered / sorted tracks (memoised)
@@ -933,7 +940,7 @@ export class TrackList extends LitElement implements SelectionHost, ContextMenuH
       overflow-y: auto;
       user-select: none;
       contain: paint;
-      will-change: transform;
+      overflow-anchor: none;
     }
 
     .track-row {
@@ -947,6 +954,8 @@ export class TrackList extends LitElement implements SelectionHost, ContextMenuH
       cursor: default;
       user-select: none;
       overflow: hidden;
+      height: 33px;
+      box-sizing: border-box;
     }
 
     .track-row > * {
@@ -1227,7 +1236,16 @@ export class TrackList extends LitElement implements SelectionHost, ContextMenuH
             }
         }
 
-        this.libraryCtrl.setScrollPosition('tracks', first);
+        // RAF-throttle scroll position saves — at most once per frame.
+        // Without this, every visibilityChanged (fired per-item during
+        // scroll) writes to the store synchronously, adding main-thread
+        // work during the scroll hot path.
+        if (this.scrollSaveRAFId === null) {
+            this.scrollSaveRAFId = requestAnimationFrame(() => {
+                this.scrollSaveRAFId = null;
+                this.libraryCtrl.setScrollPosition('tracks', first);
+            });
+        }
     };
 
     // =================================================================
@@ -1640,6 +1658,7 @@ export class TrackList extends LitElement implements SelectionHost, ContextMenuH
 
         // No inline closures — all events delegated via data-index
         // on the virtualizer element (see firstUpdated).
+        const term = this.searchCtrl.term;
         return html`
       <div
         class=${classMap({
@@ -1661,26 +1680,23 @@ export class TrackList extends LitElement implements SelectionHost, ContextMenuH
             variant=${favVariant}
           ></wa-icon>
         </div>
-        ${(() => {
-                const term = this.searchCtrl.term;
-                return cols.map((col) => {
-                    const val = col.accessor(track);
-                    const centered = val === '\u2014';
-                    const display = term
-                        ? highlightText(val, term)
-                        : val;
+        ${cols.map((col) => {
+                const val = col.accessor(track);
+                const centered = val === '\u2014';
+                const display = term
+                    ? highlightText(val, term)
+                    : val;
 
-                    return html`
-                        <div class=${classMap({
-                            cell: true,
-                            'cell-center': centered,
-                            'cell-right': !centered && col.align === 'right',
-                        })}>
-                            ${display}
-                        </div>
-                    `;
-                });
-            })()}
+                return html`
+                    <div class=${classMap({
+                        cell: true,
+                        'cell-center': centered,
+                        'cell-right': !centered && col.align === 'right',
+                    })}>
+                        ${display}
+                    </div>
+                `;
+            })}
       </div>
     `;
     };

frontend/wailsjs/go/library/Library.d.ts

@@ -59,3 +59,5 @@ export function SetContext(arg1:context.Context):Promise<void>;
 export function SetRemovalHooks(arg1:library.RemovalHooks):Promise<void>;
 
 export function SetRescanHooks(arg1:library.RescanHooks):Promise<void>;
+
+export function SoftScanAllLibraries():Promise<void>;

frontend/wailsjs/go/library/Library.js

@@ -113,3 +113,7 @@ export function SetRemovalHooks(arg1) {
 export function SetRescanHooks(arg1) {
   return window['go']['library']['Library']['SetRescanHooks'](arg1);
 }
+
+export function SoftScanAllLibraries() {
+  return window['go']['library']['Library']['SoftScanAllLibraries']();
+}

frontend/wailsjs/go/models.ts

@@ -137,7 +137,7 @@ export namespace library {
 	export class ScanWarning {
 	    filePath: string;
 	    phase: string;
-	    err: any;
+	    err: string;
 	
 	    static createFrom(source: any = {}) {
 	        return new ScanWarning(source);