New internal/rotator/dcu1 client speaking the DCU-1 command set (AP1nnn / AM1
to go-to, AI1 to read bearing), over a serial COM port (4800 baud default) or a
raw TCP serial-over-IP bridge. Azimuth-only; Stop re-commands the current
bearing since the base set has no stop opcode.
Wired through app.go (normRotorType, default port 4001, GoTo/Heading/Stop/test
switches, park returns the same "PstRotator only" note as ARCO) and exposed in
the rotor settings as "Hy-Gain DCU-1 (RotorCard DXA, Rotor-EZ, Green Heron)"
with the ARCO's serial/TCP transport chooser and a bilingual hint. Protocol is
implemented from the standard DCU-1 spec and still needs field confirmation
against a real RotorCard DXA.