bbctrl.AuxAxis manages a stepper driven by an auxcnc-style ESP32
over /dev/ttyUSB0 (or whichever serial port). Persistent config in
aux.json; UI talks to it via /api/aux/* endpoints.
- AuxAxis: serial framing, position tracking, soft-limit enforcement,
homing state machine, ATC pneumatic control (M100..M103 wrappers).
- Ctrl: instantiate self.aux alongside the other subsystems and
close it during shutdown.
- Web: handlers for /api/aux/{config,status,home,abort,jog,move,set-zero}.
Henrik Muehe
d797f1d4fc