feat: let the viewer pick the audio track

The streaming path mapped 0:a:0 unconditionally, so a dubbed film played in
whichever language was muxed first and the others were unreachable. The node
now enumerates the tracks in stream_init and honours audio_track in
stream_req; switching is the seek path, since one ffmpeg carries one track.

MNP 3.2, additive: the player draws its selector from the node's own list and
never from a version number, so an older node is never asked for a track it
would ignore. MNP_MIN_SUPPORTED does not move.

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

1 files changed, 8 insertions, 8 deletions

diff --git a/packages/meshbay-node/tests/test_stream_video_transcode.py b/packages/meshbay-node/tests/test_stream_video_transcode.py
index 69f4c2d..b165af4 100644
--- a/packages/meshbay-node/tests/test_stream_video_transcode.py
+++ b/packages/meshbay-node/tests/test_stream_video_transcode.py
@@ -191,10 +191,10 @@ async def test_probe_video_reports_raw_codec_name_for_hevc(tmp_path):
     clip = tmp_path / "clip.mkv"
     _make_hevc_clip(clip)
 
-    codec, duration, has_audio, width, height, raw_codec = await _probe_video(str(clip))
+    probe = await _probe_video(str(clip))
 
-    assert raw_codec == "hevc"
-    assert codec is not None and codec.startswith("hev1.")
+    assert probe.raw_codec_name == "hevc"
+    assert probe.codec is not None and probe.codec.startswith("hev1.")
 
 
 @needs_mp3
@@ -206,13 +206,13 @@ async def test_probe_video_reports_no_codec_string_for_mpeg4(tmp_path):
     clip = tmp_path / "clip.avi"
     _make_mpeg4_clip(clip)
 
-    codec, duration, has_audio, width, height, raw_codec = await _probe_video(str(clip))
+    probe = await _probe_video(str(clip))
 
-    assert raw_codec == "mpeg4"
-    assert codec is None, (
+    assert probe.raw_codec_name == "mpeg4"
+    assert probe.codec is None, (
         "a codec string for MPEG-4 Part 2 would be one no browser can act on")
-    assert has_audio is True
-    assert (width, height) == (320, 240)
+    assert probe.has_audio is True
+    assert (probe.width, probe.height) == (320, 240)
 
 
 @needs_mp3