Clean up object URLs in dispose() method

When a Webamp instance is disposed, clean up all object URLs from tracks
and album art to prevent memory leaks. This ensures proper cleanup when
the instance is destroyed, complementing the per-track cleanup that
happens during normal operation.

Author: claude

packages/webamp/js/webampLazy.tsx

@@ -528,6 +528,18 @@ class Webamp {
    * attempt to clean itself up to avoid memory leaks.
    */
   dispose(): void {
+    // Clean up all object URLs to prevent memory leaks
+    const state = this.store.getState();
+    const tracks = Selectors.getTracks(state);
+    Object.values(tracks).forEach((track) => {
+      if (track.url && track.url.startsWith("blob:")) {
+        URL.revokeObjectURL(track.url);
+      }
+      if (track.albumArtUrl && track.albumArtUrl.startsWith("blob:")) {
+        URL.revokeObjectURL(track.albumArtUrl);
+      }
+    });
+
     this.media.dispose();
     this._actionEmitter.dispose();
     this._disposable.dispose();