fix(player): reset WaveformSeek interpolation anchor on resume (#486)

The interpolation effect unmounts while paused, so progressAnchorRef.atMs was
never refreshed. The first tick after play added the entire pause duration to
elapsedSec and overshot the playhead until the next transport heartbeat.
Re-anchor from getPlaybackProgressSnapshot() when the effect starts.

src/components/WaveformSeek.tsx

@@ -1212,6 +1212,22 @@ export default function WaveformSeek({ trackId }: Props) {
 
   useEffect(() => {
     if (!isPlaying || previewFreezesMainSeekbar || duration <= 0 || !isFinite(duration)) return;
+    // This effect is torn down while paused, so `progressAnchorRef.atMs` is not refreshed.
+    // On resume the first `tick` would add the entire pause duration to `elapsedSec` and
+    // overshoot the playhead until the next transport heartbeat corrects it.
+    const snap = getPlaybackProgressSnapshot();
+    const raw = snap.progress;
+    progressRef.current = raw;
+    progressAnchorRef.current = {
+      progress: raw,
+      atMs: performance.now(),
+    };
+    const resumeVisual = isBarQuantizedSeekStyle(styleRef.current)
+      ? quantizeProgressByBars(raw)
+      : raw;
+    visualTargetProgressRef.current = resumeVisual;
+    visualProgressRef.current = resumeVisual;
+
     let rafId: number | null = null;
     let lastPaintAt = 0;
     const tick = (now: number) => {