Run stations as root with launch on boot

Test stations that need root access to their hardware can now start automatically at boot. Previously enabling launch on boot as root failed because the station installed a user-level service.

• Added automatic system-service install when the station runs as root, so launch on boot works without a login session.
• Hid the on-screen kiosk option for root stations, which have no display, and made clear that these stations are controlled from the dashboard.
• Showed a clear, actionable message instead of a raw systemd error when launch on boot cannot be enabled.