Add a mako notification daemon module to the desktop group, enabled by
the aggregator. Toasts auto-dismiss into history after five seconds, a
do-not-disturb mode ([mode=dnd] invisible=true) suppresses display while
still recording to history, and Super+N recalls the last notification
via makoctl restore. Colors and the popup font come from Stylix's mako
target. The bar-side do-not-disturb toggle and media controls already
live in waybar.nix, so this task adds only the daemon.
