fix(local): Fix local_runtime use with free-threaded python

[laramiel]

• Return abi_flags from get_local_runtime_info and pass it into the py3_runtime
• Rework how shared-libraries are links are constructed to better meet @rules_cc cc_library.srcs requirements

This improves runtime detection for macos when using a python3.14t framework runtime.

[gemini-code-assist]

Summary of Changes

Hello @laramiel, 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 addresses an issue with local Python runtime detection, especially on macOS with free-threaded Python builds. It introduces explicit handling of Python's Application Binary Interface (ABI) flags and refines the shared library linking process. By accurately identifying and passing ABI information and ensuring correct library symlinking, the changes improve the robustness and compatibility of Python runtime configurations within the build system.

Highlights

• ABI Flags Integration: Application Binary Interface (ABI) flags are now correctly retrieved from the local Python runtime and passed into the py3_runtime definition, which is crucial for distinguishing different Python builds (e.g., free-threaded versions).
• Shared Library Linking Rework: The mechanism for constructing shared library links has been revised to better align with @rules_cc's cc_library.srcs requirements, improving build compatibility and robustness.
• Improved macOS Runtime Detection: These changes specifically enhance runtime detection on macOS, particularly for Python versions utilizing framework runtimes like python3.14t, ensuring more accurate configuration.

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[gemini-code-assist]

Code Review

This pull request introduces support for free-threaded Python by adding abi_flags to the local runtime information. The changes include refactoring the logic for discovering Python libraries in get_local_runtime_info.py, making it more robust and maintainable. Specifically, the shared library suffix detection is centralized, and the library search paths are expanded. The abi_flags are then propagated through the Bazel rules to correctly configure the Python toolchain. Additionally, the logic for symlinking shared libraries in local_runtime_repo.bzl has been generalized to better support different platforms, especially macOS framework builds. The changes are well-structured and effectively address the goal of improving runtime detection for newer Python versions. The code quality is high, and the refactoring improves maintainability. I have no comments on any issues to address.

[rickeylev]

Can you clarify what "Rework how shared-libraries are links are constructed to better meet @rules_cc cc_library.srcs requirements"

What requirement does it have that wasn't being properly met?

[rickeylev]

Just needs a changelog entry, but otherwise LGTM