Party should be a share action target for other apps to add music to a party

[chances]

Party should allow other apps, specifically Spotify, to share tracks, albums, and artists to the host's current party. If a shared payload is a Spotify URL/URI then present a UI to let the user add the song(s) to the current party's queue. If the shared payload is something else, begin searching for a track, album, or artist with the text.

Handle share (ACTION_SEND) intents from other apps

Flutter-specific guide (How do I handle incoming Intents from external applications in Flutter)

Android docs - Receiving Simple Data from Other Apps

Add an activity to support a cust share action label?