feat(lekiwi): support LeKiwi in lerobot-replay CLI (#3739)

Register the `lekiwi` robot module in `lerobot_replay.py` so episodes can be
replayed on a LeKiwi via `--robot.type=lekiwi_client`. The module is already
registered in `lerobot_calibrate.py` and `lerobot_setup_motors.py`; this fills
the gap so the replay CLI recognizes the same robot.

Replayed actions are loaded from the dataset as torch tensors, which
`json.dumps` cannot serialize when `LeKiwiClient.send_action` ships them over
ZMQ. Coerce each action value to a plain float before sending. This is scoped
to the LeKiwi network client and does not affect any other robot.

Co-authored-by: Steven Palma <imstevenpmwork@ieee.org>

src/lerobot/robots/lekiwi/lekiwi_client.py

@@ -323,6 +323,10 @@ class LeKiwiClient(Robot):
             np.ndarray: the action sent to the motors, potentially clipped.
         """
 
+        # Action values may be torch tensors (e.g. replayed from a dataset) or numpy
+        # scalars; json.dumps only serializes Python primitives, so coerce each value to a
+        # plain float before sending.
+        action = {key: float(value) for key, value in action.items()}
         self.zmq_cmd_socket.send_string(json.dumps(action))  # action is in motor space
 
         # TODO(Steven): Remove the np conversion when it is possible to record a non-numpy array value

src/lerobot/scripts/lerobot_replay.py

@@ -61,6 +61,7 @@ from lerobot.robots import (  # noqa: F401
     earthrover_mini_plus,
     hope_jr,
     koch_follower,
+    lekiwi,
     make_robot_from_config,
     omx_follower,
     openarm_follower,