Autoplay semantics for voice messages

Fixes https://github.com/vector-im/element-web/issues/18804
Fixes https://github.com/vector-im/element-web/issues/18715
Fixes https://github.com/vector-im/element-web/issues/18714
Fixes https://github.com/vector-im/element-web/issues/17961

src/audio/Playback.ts

@@ -117,6 +117,8 @@ export class Playback extends EventEmitter implements IDestroyable {
     }
 
     public destroy() {
+        // Dev note: It's critical that we call stop() during cleanup to ensure that downstream callers
+        // are aware of the final clock position before the user triggered an unload.
         // noinspection JSIgnoredPromiseFromCall - not concerned about being called async here
         this.stop();
         this.removeAllListeners();
@@ -177,9 +179,12 @@ export class Playback extends EventEmitter implements IDestroyable {
 
         this.waveformObservable.update(this.resampledWaveform);
 
-        this.emit(PlaybackState.Stopped); // signal that we're not decoding anymore
         this.clock.flagLoadTime(); // must happen first because setting the duration fires a clock update
         this.clock.durationSeconds = this.element ? this.element.duration : this.audioBuf.duration;
+
+        // Signal that we're not decoding anymore. This is done last to ensure the clock is updated for
+        // when the downstream callers try to use it.
+        this.emit(PlaybackState.Stopped); // signal that we're not decoding anymore
     }
 
     private onPlaybackEnd = async () => {