Add three MIDI-bindable item actions mirroring the track tag family, routed
through the shared hookcommand: retag selected items' membership then re-drive
mint/apply so each lands on its mode's managed lane (manual-lane items exempt),
all in one undo block. Extract shared item_read seam, simplify applyMintPlan's
lane-count pass, and guard reconcile against unregistered-mode lanes.
