Cut removes immediately; scrollbar click-to-jump

Ctrl-X now removes the track from the playlist right away (so it visibly
leaves) and a paste re-inserts it at the target — replacing the earlier
deferred-move design (dropped move_tracks_between_playlists and the MIME
cut flag). A cut from the library is still just a copy. Separately, a
left-click on any scrollbar trough now jumps to that spot instead of
paging, via an app-wide ClickToJumpScrollStyle proxy.

lintunes/library_manager.py

@@ -234,39 +234,6 @@ class LibraryManager(QObject):
         self._set_track_ids(pid, after)
         self._push_track_ids("Reorder Playlist", pid, before, after)
 
-    def move_tracks_between_playlists(self, src_pid: str, src_rows: list[int],
-                                     dest_pid: str, dest_position: int | None = None):
-        """Cut tracks out of one playlist and insert them into another as a
-        single undoable move (Ctrl-X / Ctrl-V across playlists). For the same
-        playlist, use move_tracks_in_playlist instead."""
-        src = self.library.playlists.get(src_pid)
-        dest = self.library.playlists.get(dest_pid)
-        if (not src or not dest or src_pid == dest_pid
-                or dest.playlist_type == PlaylistType.FOLDER):
-            return
-        src_before = list(src.track_ids)
-        dest_before = list(dest.track_ids)
-        rows = sorted(set(r for r in src_rows if 0 <= r < len(src_before)))
-        if not rows:
-            return
-        moving = [src_before[r] for r in rows]
-        src_after = [tid for i, tid in enumerate(src_before) if i not in rows]
-        dest_after = list(dest_before)
-        if dest_position is None or dest_position >= len(dest_after):
-            dest_after.extend(moving)
-        else:
-            dest_after[dest_position:dest_position] = moving
-
-        def apply(src_ids, dest_ids):
-            self._set_track_ids(src_pid, src_ids)
-            self._set_track_ids(dest_pid, dest_ids)
-
-        apply(src_after, dest_after)
-        self.undo_stack.push(Command(
-            "Move to Playlist",
-            undo=lambda: apply(src_before, dest_before),
-            redo=lambda: apply(src_after, dest_after)))
-
     def _set_track_ids(self, pid: str, ids: list[int]):
         playlist = self.library.playlists.get(pid)
         if playlist is None: