Building orcacad-deps from this Dockerfile removes the snaporca-deps base, which is the point
(Trap 1: the old image's baked tree was project(Snapmaker_Orca)) — but that base was also where
Xvfb, openbox, xdotool and scrot came from. Without them gui-session.sh reports display DOWN and
orca-slicer dies with a trace trap on no display. Verified: the session now comes up with
display up, wm up, and the Untitled - OrcaSlicer window present.