The playlist view's multi-select toolbar gains "Remove from playlist" for
the owner of the open playlist, behind a confirm modal that names the
count. One dispatcher (`playlist_remove_tracks`) routes the picked row ids
by the open document's kind: a local playlist removes by stored position
(descending, one blocking pass, then reload); a mixed playlist drops its
sidecar rows and batches the remaining catalog ids into a single
`remove_tracks_from_playlist` call with an optimistic document patch.
Row positions are resolved before any delete so the compaction the local
repo performs after each removal cannot shift a later target.
cc
vicrodh
e0e1bdfbee