fix(seekbar): commit seek on mouseup + ignore progress ticks while dragging

Ports the WaveformSeek UX changes from PR #219 (original fix by @cucadmuh)
onto test/seekable-streaming:

- Split previewFraction (during drag) / commitSeek (on mouseup) so audio_seek
  fires once per gesture instead of on every mousemove.
- Subscribe-effect skips external progress updates while isDragging — prevents
  cursor flicker from streaming/recovery ticks fighting the dragged position.
- Clear seekTarget in seek() catch branch so a failed seek doesn't permanently
  block progress updates.

Skips the byte-restart fast-path from #219: would defeat RangedHttpSource's
direct seek by restarting the stream after 450ms.

Co-Authored-By: cucadmuh <cucadmuh@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/WaveformSeek.tsx

@@ -832,6 +832,9 @@ export default function WaveformSeek({ trackId }: Props) {
   useEffect(() => {
     return usePlayerStore.subscribe((state, prev) => {
       if (state.progress === prev.progress && state.buffered === prev.buffered) return;
+      // While user drags, keep the local preview stable. External progress ticks
+      // during streaming/recovery would otherwise fight the cursor and flicker.
+      if (isDragging.current) return;
       progressRef.current = state.progress;
       bufferedRef.current = state.buffered;
       if (!ANIMATED_STYLES.has(styleRef.current)) {
@@ -890,15 +893,23 @@ export default function WaveformSeek({ trackId }: Props) {
   trackIdRef.current = trackId;
   const seekRef = useRef(seek);
   seekRef.current = seek;
+  const pendingSeekRef = useRef<number | null>(null);
 
-  // Seek to a 0–1 fraction: draw immediately for 1:1 responsiveness, then
-  // let the store + Rust catch up asynchronously.
-  const seekToFraction = (fraction: number) => {
+  // Preview a 0–1 fraction while dragging: draw immediately for 1:1
+  // responsiveness; the actual seek is committed on mouseup.
+  const previewFraction = (fraction: number) => {
     progressRef.current = fraction;
+    pendingSeekRef.current = fraction;
     const canvas = canvasRef.current;
     if (canvas && !ANIMATED_STYLES.has(styleRef.current)) {
       drawSeekbar(canvas, styleRef.current, heightsRef.current, fraction, bufferedRef.current);
     }
+  };
+
+  const commitSeek = () => {
+    const fraction = pendingSeekRef.current;
+    if (fraction === null) return;
+    pendingSeekRef.current = null;
     seekRef.current(fraction);
   };
 
@@ -907,10 +918,14 @@ export default function WaveformSeek({ trackId }: Props) {
       const canvas = canvasRef.current;
       if (!canvas || !trackIdRef.current) return;
       const rect = canvas.getBoundingClientRect();
-      seekToFraction(Math.max(0, Math.min(1, (clientX - rect.left) / rect.width)));
+      previewFraction(Math.max(0, Math.min(1, (clientX - rect.left) / rect.width)));
     };
     const onMove = (e: MouseEvent) => { if (isDragging.current) seekFromX(e.clientX); };
-    const onUp   = () => { isDragging.current = false; };
+    const onUp   = () => {
+      if (!isDragging.current) return;
+      isDragging.current = false;
+      commitSeek();
+    };
     window.addEventListener('mousemove', onMove);
     window.addEventListener('mouseup',   onUp);
     return () => {
@@ -935,7 +950,7 @@ export default function WaveformSeek({ trackId }: Props) {
         onMouseDown={e => {
           isDragging.current = true;
           const rect = e.currentTarget.getBoundingClientRect();
-          seekToFraction(Math.max(0, Math.min(1, (e.clientX - rect.left) / rect.width)));
+          previewFraction(Math.max(0, Math.min(1, (e.clientX - rect.left) / rect.width)));
         }}
         onMouseMove={e => {
           if (!trackId) return;

src/store/playerStore.ts

@@ -1427,6 +1427,9 @@ export const usePlayerStore = create<PlayerState>()(
           seekDebounce = null;
           seekTarget = time;
           invoke('audio_seek', { seconds: time }).catch((err: unknown) => {
+            // Release the progress-tick guard so the UI doesn't freeze
+            // waiting for a target the engine will never reach.
+            seekTarget = null;
             const msg = String(err ?? '');
             if (!msg.includes('not seekable')) {
               console.error(err);