fix(audio): guard underrun/stream-complete against false end-of-playback

pause() clears underrun_ so setStreamComplete can't fire TrackEnded while paused; resetToStart() resets streamComplete. Prior fix: underrun_ park + streamComplete discriminator prevent the Opus-startup false-end. Tests: 18 PlaybackScheduler cases including pause-during-underrun and underrun->resume->genuine-end-once.

DeepDrftPublic.Client/Services/StreamingAudioPlayerService.cs

@@ -138,6 +138,12 @@ public class StreamingAudioPlayerService : AudioPlayerService, IStreamingPlayerS
     // Organic end-of-stream closes the session; the bucket reflects the high-water fraction reached.
     protected override void OnPlaybackEnded() => _playTracker?.Close();
 
+    // [RELOAD-DIAG] Emit the tagged log at each base-class Duration-null site so a run unambiguously
+    // shows which path nulled Duration between two "Duration set from header" lines. Trivially removable.
+    protected override void OnDurationNulledDiag(string caller) =>
+        _logger.LogInformation(
+            "[RELOAD-DIAG] Base nulling Duration caller={Caller} (gen={Gen})", caller, _loadGeneration);
+
     public override async Task SelectTrack(TrackDto track)
     {
         await SelectTrackStreaming(track);