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- Add `joint-actuatorforcerange` for clamping total actuator force at joints. Add `sensor-jointactuatorfrc` for sensing total actuator forces on a single joint. See [documentation](https://mujoco.readthedocs.io/en/latest//modeling.html#actuator-force-clamping) for justification and use cases. - Add simple car model to `model/`. - Move actuation-related test models into `engine/testdata/actuation/`. PiperOrigin-RevId: 549355941 Change-Id: I27f6c1f80426d73a2811ef5ae74684a228b2fbd1