Renders /@:username/playlists/:slug, for anyone who may see the playlist: a private one only to its owner. usePlaylist loads it, by a former name or slug too, and keeps it live. Its owner, or a user with playlist:moderate, can drag its dumps into a new order and remove one, with a short window to undo, edit its title and description in place, and edit the rest or delete it in the editor that opens over its header at /@:username/playlists/:slug/edit. Both paths render the page at the same place, so opening the editor keeps the playlist loaded. Anyone else there gets the page, or is asked to sign in first.

Passed to PlaylistDetail by App's route.