unitreerobotics/unitree_ros — reverse-engineered prompt

Build me a ROS workspace for simulating Unitree robots in Gazebo. I want to load Unitree robot models, view them in RViz, and launch a Gazebo world like earth, space, or stairs with robots such as Laikago, A1, Aliengo, or Go1. The simulation should let me command the joints directly with position, velocity, and torque, run a simple stand controller, move the robot pose around for SLAM or vision testing, and apply an outside push so I can see how it reacts.

Please include the robot descriptions, meshes, URDF or xacro files, Gazebo launch files, and joint controller examples. Make it work in a normal catkin workspace with ROS Melodic and Gazebo 8. Add clear setup notes for installing ROS dependencies, fixing the stairs world path on my computer, building with catkin_make, and running the main launch and control commands. If you need current ROS or Gazebo details, look them up online.