Fix audio context and microphone listener cleanup leaks

[zortos293]

This PR fixes memory/resource leaks in the WebRTC audio and microphone management paths by ensuring explicit cleanup of native audio objects and stream listeners.

Main changes:

• GfnWebRtcClient (opennow-stable/src/renderer/src/gfn/webrtcClient.ts):

  • Added audioSourceNode field to track the MediaStreamAudioSourceNode used for remote audio routing.
  • Introduced cleanupAudioRouting() helper to idempotently disconnect the source node, close the AudioContext, and reset the audio element state.
  • Modified cleanupPeerConnection() to call cleanupAudioRouting() instead of inline logic.
  • Updated audio track attachment to build the routing graph using local variables first; instance fields are only assigned after successful setup.
  • On setup failure or fallback, partially created objects are now cleaned up before startDirectAudioPlayback() is invoked.

• MicrophoneManager (opennow-stable/src/renderer/src/gfn/microphoneManager.ts):

  • Replaced the anonymous inactive stream listener with a stable, stored handler (handleMicStreamInactive).
  • Added attachMicStream(), detachMicStreamListeners(), and clearMicStream() helpers to manage listener lifecycle.
  • Modified startCapture() to clear previous streams and attach listeners via attachMicStream().
  • Updated stop() to use clearMicStream() instead of inline cleanup.
  • Ensured the OverconstrainedError fallback path also attaches listeners correctly.