release jitter buffer entries as they are consumed

Packets are removed from the jitter buffer by resliceing past them, which
leaves the popped entries in the backing array. Each one pins a decoded
audio frame until the array is next reallocated.

Clear the slot before resliceing.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

gumble/gumbleopenal/stream.go

@@ -613,6 +613,9 @@ func (s *Stream) OnAudioStream(e *gumble.AudioStreamEvent) {
 				return nil
 			}
 			p := jitterBuf[0]
+			// Clear the slot before resliceing: the popped entries stay in
+			// the backing array otherwise, pinning a decoded frame each.
+			jitterBuf[0] = nil
 			jitterBuf = jitterBuf[1:]
 			jitterDuration -= audioPacketDuration(p)
 			// Frame numbers are Mumble timestamps in 10 ms units.
@@ -694,6 +697,7 @@ func (s *Stream) OnAudioStream(e *gumble.AudioStreamEvent) {
 									jitterBuf[0].Sequence, e.User.Name, jitterNextSeq, len(jitterBuf))
 							}
 							jitterDuration -= audioPacketDuration(jitterBuf[0])
+							jitterBuf[0] = nil
 							jitterBuf = jitterBuf[1:]
 							continue
 						}