droiddeck-gpu runs a program in a gamescope of its own on the app's compositor
(wayland-0), full screen over the desktop - the path the rail's play chips use,
where Vulkan works. droiddeck-desktop-gpu gives every Game/Emulator menu entry a
per-user copy through it (auto: while the desktop is on pixman), keeping 'Run in
a desktop window' as an action.
droiddeck-desktop loads /usr/local/lib/droiddeck-wlroots for the vulkan/gles2
renderers and falls back to pixman when labwc stops at start. The build stages
the wlroots release named by tools/wlroots/release.env, once published.