Drag teaching is not implemented

This stack does not implement drag teaching (拖动遥操作): no physical drag-to-teach path, no trajectory record/playback, and no enter_teach_mode API.

Implemented teleop for HighTorque Panthera HT is master–slave isomorphic teleop (同构遥操作). On the panthera-ht branch that is ./teleop_start.sh — see HighTorque Panthera HT. The package is still named drag_teleop_controller; follow Isomorphic Teleop.