Porf: modify URDF path handling: Pass from urdf_cfg to solver_cfg

[chase6305]

Description

fix: #133

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 issue #133 where PinkSolver fails when using the URDF assembly tool to build a robot from multiple components. The root cause is that when multiple URDF components are assembled, the assembled URDF path differs from the individual component paths, and solvers need to reference the assembled URDF path rather than the original component paths. This change automatically propagates the assembled URDF path from urdf_cfg to solver_cfg configurations when the solver's urdf_path is None.

Changes:

• Automatically set solver_cfg.urdf_path to the assembled URDF path when it's None and urdf_cfg is used

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.