feat(desktop): add the rofi launcher (task 0024)

Add a rofi module to the desktop group, enabled by the aggregator.
It runs the drun application launcher, bound on Super+R. A session menu
built on the same themed rofi is bound on Super+Shift+X, and every
rofi -dmenu call inherits the Stylix theme, so later utility menus
reuse it for free.

Also give layer surfaces their own fade-in (layersIn and fadeLayersIn)
at the window animation speed, so the launcher fades in quickly rather
than snapping into place.

.claude/tasks/0024-rofi-launcher.md

@@ -33,4 +33,3 @@ Structure it so it is reusable as the dmenu-style frontend for later utility men
 - The power menu is bound to `Super+Shift+X`, chosen by the operator.
   It pairs with lock on `Super+X` (a key the spec's table does list), while the parent spec's table has no power-menu key of its own.
 - No Waybar `window-rewrite` icon mapping was added: rofi renders as a Wayland layer-shell overlay, not a tiled window with a class on a workspace, so it never appears on the workspace indicator the convention governs.
-- The launcher's quick appearance is a Hyprland change, not a rofi one: layer surfaces get their own `layersIn`/`fadeLayersIn` fade at `2`, a step quicker than the `3` windows use, so the launcher fades in without feeling laggy.