fix(transport): remove removeTrack loop before close to prevent crashes

removeTrack nulls sender tracks and changes transceiver directions,
causing PeerConnection::Close() to skip ClearSend/DetachTrack in its
StopTransceiverProcedure and hit edge cases in the worker-thread
teardown (ICE use-after-free, AVAudioEngine deallocation assertion).
Close() handles full cleanup on its own. The loop was originally
commented out as "not required?" and was accidentally uncommented
during a threading refactor (101e09d).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: pblazej

Sources/LiveKit/Core/Transport.swift

@@ -204,11 +204,12 @@ actor Transport: NSObject, Loggable {
 
         // Stop listening to delegate
         _pc.delegate = nil
-        // Remove all senders (if any)
-        for sender in _pc.senders {
-            _pc.removeTrack(sender)
-        }
 
+        // Do not call removeTrack before close — it nulls sender tracks and
+        // changes transceiver directions, causing Close() to skip ClearSend/
+        // DetachTrack in its StopTransceiverProcedure and hit edge cases in
+        // the worker-thread teardown (ICE use-after-free, AVAudioEngine
+        // deallocation assertion). Close() handles full cleanup on its own.
         _pc.close()
     }
 }