dartsim/dart ? reverse-engineered prompt

Build me a research focused physics engine for robotics, animation, and machine learning, with both C++ and Python support.

I want it to let me create a world, add rigid bodies, step the simulation, and inspect things like position, time, kinematics, dynamics, collisions, and constraints. It should be able to load common robot and simulation models like URDF, SDF, and MJCF, and it should be useful for articulated systems, inverse kinematics, and rigid body dynamics, not just a toy demo.

Please make it feel like a serious open source library, with clear docs, a few examples and tutorials, and tests that show the basic simulation flow works. If you need to check current docs or patterns online while wiring up the API, go ahead. I’d like the Python side to be easy to use, but the core should stay clean and modern in C++23.