gh-145563: Add thread-safety annotation for PyCapsule

[eendebakpt]

• Skip news (similar to related PRs).
• PR made using assistance from Claude code.

• Issue: Thread safety of PyCapsule #145563

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📚 Documentation preview 📚: https://cpython-previews--146612.org.readthedocs.build/

[miss-islington-app]

Thanks @eendebakpt for the PR, and @kumaraditya303 for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖

[bedevere-app]

GH-146659 is a backport of this pull request to the 3.14 branch.

[PPPDUD]

@eendebakpt What do you mean when you say that it was assisted by Claude? Do you mean to say that it wrote some portions of the code, that it helped with debugging and/or planning, or both?

[eendebakpt]

@eendebakpt What do you mean when you say that it was assisted by Claude? Do you mean to say that it wrote some portions of the code, that it helped with debugging and/or planning, or both?

Why are you asking? There is no code in this PR, just labels for the thread-safety. In this case, asked Claude for his opinion on which labels should be added for the PyCapsule methods. For some I requested additional explanation, some I manually changed.

[PPPDUD]

@eendebakpt What do you mean when you say that it was assisted by Claude? Do you mean to say that it wrote some portions of the code, that it helped with debugging and/or planning, or both?

Why are you asking? There is no code in this PR, just labels for the thread-safety. In this case, asked Claude for his opinion on which labels should be added for the PyCapsule methods. For some I requested additional explanation, some I manually changed.

I'm a user who depends on CPython to use my computer (Ubuntu), so I was curious about how LLMs were being used in the highly-important codebase that me and many others rely upon every day of our lives.