perf(tracklist): drop now-playing pulse + EQ-bar animations (#488)

* perf(tracklist): replace animated EQ-bar + active-row pulse with static icon

The currently-playing track in any tracklist (AlbumDetail, ArtistDetail,
PlaylistDetail, Favorites, RandomMix) was rendered with two animations
on top of an already-busy DOM:

- `.track-row.active` ran `track-pulse` 3s opacity 1 → 0.6 → 1 infinite
  on the entire row subtree (title button, several Lucide icons, star
  rating SVGs, hover affordances). Opacity is a compositor property, but
  on WebKitGTK without compositing — Linux + NVIDIA proprietary +
  WEBKIT_DISABLE_COMPOSITING_MODE=1 — every animated row falls back to a
  full software repaint of the subtree per frame.
- The "now playing" indicator in the track-number cell was three
  `<span class="eq-bar">` siblings with `transform: scaleY()` keyframes
  (`eq-bounce`), each on its own delay/duration. Same composite story:
  three software-repainted layers per frame, every frame.

On AlbumDetail (long tracklist + cover-art header background + the
already-running WaveformSeek progress rAF in the player bar) the
combined cost held the WebProcess at ~80 % CPU with 1.2 GB RSS for the
entire duration of playback. CPU dropped immediately on pause/stop;
on Composers / Settings (no track rows) the symptom never appeared.
Profiler confirmed continuous Layout & Rendering work synchronised with
isPlaying, not the canvas itself.

Replace both animations with static visuals:

- `.track-row.active` keeps the `--accent-dim` background, drops the
  pulse animation entirely.
- The "now playing" indicator becomes a single Lucide `AudioLines` icon
  (four vertical bars of different heights — reads as an EQ icon, no
  animation, one SVG per active row instead of three animated spans).
  `.eq-bars` className now only sets the accent colour.

Cleanup: dead `@keyframes track-pulse`, `@keyframes eq-bounce`,
`.eq-bars.paused` rule, plus a duplicate `.eq-bar` block in theme.css
(with a `wave` keyframe that was being shadowed by components.css and
had no other consumers).

No behaviour change beyond removing the animation; the row is still
visibly the active one and the icon still marks the playing track.

* docs: CHANGELOG entry for tracklist animation perf fix (PR #488)

src/components/AlbumTrackList.tsx

@@ -1,5 +1,5 @@
 import React, { useState, useEffect, useRef, useCallback } from 'react';
-import { Play, ChevronRight, Heart, ChevronDown, Check, RotateCcw, Square } from 'lucide-react';
+import { Play, ChevronRight, Heart, ChevronDown, Check, RotateCcw, Square, AudioLines } from 'lucide-react';
 import { useTracklistColumns, type ColDef } from '../utils/useTracklistColumns';
 import { SubsonicSong } from '../api/subsonic';
 import { Track, usePlayerStore, songToTrack } from '../store/playerStore';
@@ -136,7 +136,7 @@ const TrackRow = React.memo(function TrackRow({
             />
             {isActive && isPlaying ? (
               <span className="track-num-eq">
-                <div className="eq-bars"><span className="eq-bar" /><span className="eq-bar" /><span className="eq-bar" /></div>
+                <AudioLines className="eq-bars" size={14} />
               </span>
             ) : (
               <span className="track-num-number">{song.track ?? '—'}</span>
@@ -541,7 +541,7 @@ export default function AlbumTrackList({
                   <div className="tracklist-mobile-main">
                     {isActive && isPlaying ? (
                       <span className="tracklist-mobile-eq">
-                        <div className="eq-bars"><span className="eq-bar" /><span className="eq-bar" /><span className="eq-bar" /></div>
+                        <AudioLines className="eq-bars" size={14} />
                       </span>
                     ) : (
                       <span className="tracklist-mobile-num">{song.track ?? ''}</span>