PY api - Custom message types can't be passed to RPCs

Calling app.GO2Connection.move(Twist([...], [...]), duration=2.0) raises:

AttributeError: cannot access 'linear'
  File "rpyc/core/protocol.py", line 796, in _check_attr
    raise AttributeError(f"cannot access {name!r}")

RPyC ships the Twist object to the daemon as a netref, not a pickled copy. When the daemon-side connection.move(twist, duration) does twist.linear.x, that goes back over the wire to the client. The client side of the connection (created in dimos/porcelain/remote_module_source.py) uses RPyC's default VoidService, which has allow_public_attrs=False — so the request to read linear is rejected.

Caveat: in --replay mode the bug doesn't fire because ReplayConnection.move() is a stub that returns True without touching twist.linear. The bug only surfaces when the underlying connection actually reads attributes (real UnitreeWebRTCConnection.move, MujocoConnection.move, etc.).

Synced from DIM-836 by summer