feat(notch): Apple Music, Deezer, YouTube Music and the browser in the notch

[flotttt]

What

The notch player is no longer Spotify-only.

• Apple Music: native, through AppleScript like Spotify (title, artwork, controls, volume). Permission row in the setup window.
• Other players (experimental): Deezer, YouTube Music, a video in the browser… anything in macOS's Now Playing. A small helper
  (NowPlayingHelper.dylib) runs inside /usr/bin/perl, since macOS 15.4 only lets Apple-signed programs read Now Playing. No volume
  for these players. Option: Options › Other Players (Experimental), on by default.
• Automatic source: the notch follows the player that plays; the last one started if several play.

Also

• Fix: every player's AppleScript now runs on one shared queue. With one queue per player, Music's read could get Spotify's reply.
• Setup window: one permission row per player. "Ask Again" resets all of SonyNotch's Apple Events answers (tccutil can't do less), so
  the other allowed players are asked again.
• Notch messages, README and translations name the player instead of Spotify.

Tested

• make test green (new tests: Music replies, Now Playing lines, source picker).
• Universal release build.
• On macOS 27: Apple Music with a local file, YouTube in Brave via Now Playing, automatic switching.