Viewer: close audio player when loading a new source

Without this, mHasAudio retained the previous file's value until the
first Play() on the new file, so the volume/mute controls reflected
the last-played file instead of the current one.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: chammoru

Viewer/ViewerDoc.cpp

@@ -194,6 +194,7 @@ void CViewerDoc::LoadSourceImage(bool adjustWindow)
 	mBufferQueue->destroy();
 
 	pView->KillPlayTimer();
+	pView->mAudioPlayer.Close();
 	pView->mSelRegions.clear();
 
 	int w = mW, h = mH;