fn paste_menu(ui: &mut Ui, actions: &mut Vec<Action>)Expand description
Paste a copied group (relative times, the way presets::capture_template stores one) at at, with
fresh clip / link / marker ids. Project::place_clips picks the first track of each kind with room
(adding one when nothing is free); target then pulls the group onto the row the user last clicked,
if the whole group fits there.
The paste flavours, shared by every timeline context menu. The app decides whether the clipboard
actually holds anything — a menu that hid itself when empty would just look broken.