handlr fails to correctly identify *.m3u playlists

[zoqaeski]

When opening *.m3u playlists with handlr, it incorrectly identifies them as plain text files and opens them with my text editor instead of the application I use for music and media.

$ handlr --verbose open /tmp/beets/beetsplug_play/6y91bmas.m3u
2025-10-31T03:01:21.443971Z  INFO handlr::config::main_config: Started opening paths: ["/tmp/beets/beetsplug_play/6y91bmas.m3u"]
2025-10-31T03:01:21.443982Z  INFO handlr::config::main_config: No matching regex handlers found for `/tmp/beets/beetsplug_play/6y91bmas.m3u`
2025-10-31T03:01:21.447389Z  INFO handlr::apps::user: Not running selector, choosing first handler
2025-10-31T03:01:21.447394Z  INFO handlr::config::main_config: Match found for `text/plain` in mimeapps.list Default Associations
2025-10-31T03:01:21.447741Z  INFO handlr::config::main_config: Finished opening paths

$ handlr mime /tmp/beets/beetsplug_play/6y91bmas.m3u
┌────────────────────────────────────────┬────────────┐
│ path                                   │ mime       │
├────────────────────────────────────────┼────────────┤
│ /tmp/beets/beetsplug_play/6y91bmas.m3u │ text/plain │
└────────────────────────────────────────┴────────────┘

$ mimetype /tmp/beets/beetsplug_play/6y91bmas.m3u
/tmp/beets/beetsplug_play/6y91bmas.m3u: audio/x-mpegurl

$ handlr get .m3u
mpv.desktop

$  handlr get audio/x-mpegurl
mpv.desktop

$ cat /tmp/beets/beetsplug_play/6y91bmas.m3u
/mnt/library/Music/Artist/Album/Song 1.flac
/mnt/library/Music/Artist/Album/Song 2.flac
/mnt/library/Music/Artist/Album/Song 3.flac
/mnt/library/Music/Artist/Album/Song 4.flac
...

While technically *.m3u files are plain text files, they should be handled differently because they're a list of files or URLs to play. Perhaps handlr should check the file extension first?