fix: use ADTS for AAC transcoding, temporarily exclude AAC from transcode decisions (#5167)

* fix: use ADTS format for AAC transcoding to avoid silent output on ffmpeg 8.0+

The fragmented MP4 muxer (`-f ipod -movflags frag_keyframe+empty_moov`)
produces corrupt/silent audio when ffmpeg pipes to stdout, confirmed on
ffmpeg 8.0+. The moof atom offset values are zeroed out in pipe mode,
causing AAC decoder errors. Switch to `-f adts` (raw AAC framing) which
works reliably via pipe and is widely supported by clients including
UPnP/Sonos devices.

* fix: exclude AAC from transcode decision, as it is not working for Sonos.

Signed-off-by: Deluan <deluan@navidrome.org>

---------

Signed-off-by: Deluan <deluan@navidrome.org>

core/stream/aliases.go

@@ -80,6 +80,11 @@ func matchesCodec(codec string, codecs []string) bool {
 	return matchesWithAliases(codec, codecs, codecAliasGroups)
 }
 
+// IsAACCodec returns true if the given codec or container name resolves to AAC.
+func IsAACCodec(name string) bool {
+	return matchesCodec(name, []string{"aac"}) || matchesContainer(name, []string{"aac"})
+}
+
 func containsIgnoreCase(slice []string, s string) bool {
 	return slices.ContainsFunc(slice, func(item string) bool {
 		return strings.EqualFold(item, s)