Fix [xyz, quat] format pose ik computation for robot

[yuecideng]

Description

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist

• I have run the black . command to format the code base.
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• Dependencies have been updated, if applicable.

[Copilot]

Pull request overview

This PR fixes a critical bug in the inverse kinematics (IK) computation when using the 7-element [x, y, z, w, x, y, z] pose format (position + quaternion). The original code incorrectly called quat_from_matrix() on quaternion values, which expects a 3x3 rotation matrix as input. The fix properly uses matrix_from_quat() to convert quaternions to rotation matrices before building the 4x4 homogeneous transformation matrix.

Changes:

• Fixed compute_ik method to properly convert [xyz, quat] format poses to 4x4 matrices
• Fixed compute_batch_ik method with the same quaternion-to-matrix conversion logic
• Added test coverage to verify IK produces identical results for both matrix and [xyz, quat] pose formats

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
embodichain/lab/sim/objects/robot.py	Fixed quaternion-to-matrix conversion in compute_ik and compute_batch_ik methods by replacing incorrect quat_from_matrix calls with correct matrix_from_quat calls, and importing the required function
tests/sim/solvers/test_opw_solver.py	Added test case to verify IK computation produces consistent results for both 4x4 matrix and 7-element [xyz, quat] pose formats

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