TeleopPanel: SE(3) gizmo + ghost hand for interactive teleop (#13)

* Add TeleopPanel: SE(3) gizmo + ghost hand for interactive teleop

- GhostHand: extracts gripper collision meshes from MuJoCo model,
  merges into single trimesh, renders as transparent overlay in the
  EE frame. Generic — works for any gripper body prefix.
- TeleopPanel(PanelBase): Viser TransformControls gizmo + GUI
  (activate/deactivate, snap to EE, toggle gripper, record, safety
  mode dropdown). Drives TeleopController.set_target_pose() from
  gizmo on_update callback.
- on_sync steps the controller and updates ghost pose each frame.

* Fix: remove unsupported opacity arg from add_mesh_trimesh

* Fix ghost hand: make child of gizmo, increase gizmo scale

- Ghost mesh is now a child of the gizmo scene node — moves
  automatically when the gizmo is dragged, no manual pose updates
- Gizmo scale 0.15 → 0.3 for easier interaction

* Add debug prints for teleop callback tracing

* Step controller directly in gizmo callback, sync viewer

* Use background thread for teleop step loop

The gizmo callback runs in Viser's thread and can't safely touch
MuJoCo data. Now the callback only buffers the target pose, and a
background thread at ~30Hz calls controller.step() + viewer.sync().
The thread starts on activate and stops on deactivate.

* Remove debug prints from teleop panel

* Fix recursion: on_sync no-op, teleop loop handles stepping

* Use controller.toggle_gripper() instead of kinematic close/open

* Check controller.is_active in teleop loop

* Reset panel UI when teleop loop exits (abort/error)

* Add abort_fn to TeleopPanel, check in loop instead of controller

* Clear abort on teleop activate via clear_abort_fn

* Add status label showing tracking/collision/unreachable state

* Reset status to Idle on deactivate and loop exit

* Update safety dropdown to allow/reject

* Colored status: red for collision, orange for unreachable, markdown rendering

* Use emoji circles for status colors (no inline HTML)

* Unique gizmo names per arm for bimanual teleop

* Add shared sim lock for bimanual teleop thread safety

* Wrap each arm's controls in a labeled folder

* Cleanup: remove dead set_color(), remove on_sync no-op override

Author: siddhss5

src/mj_viser/__init__.py

@@ -2,6 +2,14 @@
 
 from mj_viser.panels import PanelBase
 from mj_viser.sensor_panel import SensorChannel, SensorPanel
+from mj_viser.teleop_panel import GhostHand, TeleopPanel
 from mj_viser.viewer import MujocoViewer
 
-__all__ = ["MujocoViewer", "PanelBase", "SensorChannel", "SensorPanel"]
+__all__ = [
+    "GhostHand",
+    "MujocoViewer",
+    "PanelBase",
+    "SensorChannel",
+    "SensorPanel",
+    "TeleopPanel",
+]