Add a screenshot module wiring grimblast (grim + slurp) through the satty
annotation editor, enabled by the desktop aggregator. Region, active-window,
and full-screen captures each open in satty and, on confirm, land in both the
clipboard and a dated file under ~/Pictures/Screenshots.
Bound to Print / Shift+Print / Ctrl+Print rather than the spec's Super+L
family, whose keys task 0021 already holds for hjkl focus and window movement.
