Is there a URL scheme for the Music app that allows me to link to a playlist?
You can use the iTunes url and append &amp;app=music.  it will look for the song or album on the iTunes catalog and start playing it locally:

https://geo.itunes.apple.com/us/album/clair-de-lune/id319190952?i=319190960&amp;mt=1&amp;app=music

Note that this plays the first of nine songs in the query response this creates.