refactor(pybind): use as_span for joint constitution bindings

[Ligo04]

Summary

• Replace manual py::list iteration with py::array_t<T> and as_span<T>() / as_span_of<T>() for numeric parameters (IndexT, Float, Vector3) across all joint constitution pybind bindings
• Affected files: fixed joint, prismatic joint, revolute joint, spherical joint, prismatic/revolute joint limits, driving prismatic/revolute joints, and external articulation constraint
• Eliminates ~140 lines of boilerplate py::cast loops, improving type safety and consistency with NumPy-native Python API

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly refactors the Pybind11 bindings for various joint constitution mechanisms. The core objective is to modernize the handling of numeric array parameters passed from Python to C++ by leveraging py::array_t and as_span utilities. This change streamlines the interface, making it more robust and performant by directly interfacing with NumPy arrays, thereby improving the overall developer experience and code maintainability.

Highlights

• Pybind11 Bindings Refactoring: Replaced manual py::list iteration with py::array_t<T> and as_span<T>() or as_span_of<T>() for numeric parameters (IndexT, Float, Vector3) across all joint constitution Pybind11 bindings.
• Improved Type Safety and Consistency: The change enhances type safety and aligns the Python API more closely with NumPy-native array handling, reducing the potential for type-related errors.
• Code Reduction: Eliminated approximately 140 lines of boilerplate py::cast loops, leading to cleaner and more concise code.
• Affected Components: This refactoring impacts fixed, prismatic, revolute, and spherical joints, as well as prismatic/revolute joint limits, driving prismatic/revolute joints, and external articulation constraints.

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[gemini-code-assist]

Code Review

This pull request refactors Pybind11 bindings across several joint-related files. It updates function signatures to accept py::array_t instead of py::list for various parameters, replacing manual iteration and casting with more efficient as_span utility calls. This change streamlines the C++ code and likely improves performance by leveraging NumPy arrays directly. The reviewer suggests consistently using curly braces for all loop bodies to enhance code clarity and prevent potential issues.