Cut (Ctrl-X) marks the selection on the clipboard with a `cut` flag; a
paste of a cut from a real playlist is a *move* (single-undo across
playlists via move_tracks_between_playlists; same-playlist reorders),
while a copy — or a cut from the library, which has nothing to remove —
just adds. Paste now inserts *above the selected track* rather than
appending. Cut/Paste added to the track context menu; parse_tracks_mime
now tolerates a None/empty clipboard.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
