refactor(unitree_g1): reduce branch to SONIC-only diff vs main

Split the onboard-controller server/handshake/thin-client work out to
feat/g1_onboard_controller and revert it here:

- unitree_g1.py: drop client + onboard roles, wireless-remote parsing and
  motion-service release; restore main's sim/socket-bridge transport. Keep only
  the SONIC integration (implicit token action/state, full-body reset/pause,
  controller kp/kd + shutdown).
- config: drop onboard/dds_interface/release_motion_control/physical_remote.
- run_g1_server.py + unitree_g1.mdx: reverted to main.
- gr00t/holosoma: keep the move into controllers/ but revert their content to
  main (only the package-relative import changes).

docs/source/unitree_g1.mdx

@@ -8,15 +8,6 @@
 
 The Unitree G1 humanoid is now supported in LeRobot! You can teleoperate, train locomanipulation policies, test in sim, and more. Both 29 and 23 DoF variants are supported.
 
-<Tip>
-  **New: SONIC whole-body control.** The `SonicWholeBodyController` runs NVIDIA's
-  [GEAR-SONIC](https://huggingface.co/nvidia/GEAR-SONIC) decoder on the G1, turning a
-  64-D latent motion token into full-body joint targets at 50 Hz. This lets you drive
-  the robot from a VLA policy trained on SONIC motion tokens (token in → whole-body
-  motion out) with `lerobot-rollout`, in sim or on the physical robot. See
-  [Whole-body control with SONIC](#whole-body-control-with-sonic) below.
-</Tip>
-
 ---
 
 ## Part 1: Getting Started
@@ -68,7 +59,7 @@ lerobot-teleoperate \
   --robot.controller=GrootLocomotionController
 ```
 
-This will launch a [MuJoCo sim instance](https://huggingface.co/lerobot/unitree-g1-mujoco/tree/main) for the G1. You can connect a gamepad to your machine before launching in order to control the robot's locomotion in sim. We support [HolosomaLocomotionController](https://github.com/amazon-far/holosoma), [GrootLocomotionController](https://github.com/NVlabs/GR00T-WholeBodyControl), and [SonicWholeBodyController](https://huggingface.co/nvidia/GEAR-SONIC) via `--robot.controller`.
+This will launch a [MuJoCo sim instance](https://huggingface.co/lerobot/unitree-g1-mujoco/tree/main) for the G1. You can connect a gamepad to your machine before launching in order to control the robot's locomotion in sim. We support both [HolosomaLocomotionController](https://github.com/amazon-far/holosoma) and [GrootLocomotionController](https://github.com/NVlabs/GR00T-WholeBodyControl) via `--robot.controller`.
 
 - Press `9` to release the robot
 - Press `7` / `8` to increase / decrease waist height
@@ -299,52 +290,6 @@ lerobot-rollout \
 
 ---
 
-## Whole-body control with SONIC
-
-The `SonicWholeBodyController` runs NVIDIA's [GEAR-SONIC](https://huggingface.co/nvidia/GEAR-SONIC)
-decoder on the G1. Each 50 Hz tick it consumes a **64-D latent motion token** and emits
-full-body joint targets — the encoder is bypassed, so a policy feeds tokens in and the
-decoder turns them into motion. Before the first token arrives the controller holds a
-neutral (idle) pose.
-
-This makes the G1 drivable by a VLA policy trained to output SONIC motion tokens (token
-as both `observation.state` and `action`, e.g. [`nepyope/sonic_walk`](https://huggingface.co/nepyope/sonic_walk))
-using the standard `lerobot-rollout`. The controller always runs **onboard** the robot;
-the laptop is a thin client that streams tokens and receives camera frames over ZMQ.
-
-**On the robot** — start the server in handshake mode so it instantiates and runs the
-controller onboard against local DDS at full rate:
-
-```bash
-cd ~/lerobot
-python src/lerobot/robots/unitree_g1/run_g1_server.py --handshake --camera
-```
-
-**From your laptop** — run the token policy; selecting `--robot.controller=SonicWholeBodyController`
-implicitly switches the robot to the 64-D latent-token action/observation interface:
-
-```bash
-lerobot-rollout \
-  --policy.path=nepyope/sonic_walk \
-  --policy.device=cuda \
-  --robot.type=unitree_g1 \
-  --robot.is_simulation=false \
-  --robot.robot_ip=<ROBOT_IP> \
-  --robot.controller=SonicWholeBodyController \
-  --robot.cameras='{"ego_view": {"type": "zmq", "server_address": "<ROBOT_IP>", "port": 5555, "camera_name": "head_camera", "width": 640, "height": 480, "fps": 30}}' \
-  --task="walk back and forth" \
-  --duration=1000 \
-  --fps=30
-```
-
-<Tip>
-  SONIC is a token-only decoder in LeRobot: the only input path is the 64-D latent
-  vector. To train your own token policy, expose the 64-D token as the action (a config
-  choice, e.g. `pi05` with a 64-D action dim) — no policy code changes are needed.
-</Tip>
-
----
-
 ## Additional Resources
 
 - [Unitree SDK Documentation](https://github.com/unitreerobotics/unitree_sdk2_python)