Replace mypy with ty for static type checking

[guan404ming]

Changes

• Bug fix
• New feature
• Refactoring
• Documentation
• Test
• CI/CD pipeline
• Other

Why

Switch to Astral's ty type checker for faster, more consistent tooling alongside ruff and uv.

How

• Replace mypy pre-commit hook with ty, add ty to dev dependencies
• Fix type errors: np.array annotation, dict.get nullability, reduce overload, stale type: ignore comments
• Configure ty to exclude CI/benchmark dirs and allow _qdp native extension imports

Checklist

• Added or updated unit tests for all changes
• Added or updated documentation for all changes

[ryankert01]

Not familiar with Ty, but looks good

[400Ping]

Overall LGTM

[400Ping]

Not familiar with it as well

[guan404ming]

FYI: https://docs.astral.sh/ty/, which is widely adopted by open source projects like tvm-ffi

[guan404ming]

Thanks!

[rich7420]

@guan404ming thanks for the patch!
A quick question: pre-commit runs ty check, but .github/workflows/python-testing.yml does not.

[rich7420]

should we add it as well?

[guan404ming]

Oops

[guan404ming]

Lol, I could add it in a follow up. Thanks for the nice catch.

[rich7420]

got it, thanks

[guan404ming]

After confirmation, we already have ci running for pre-commit, which contains the ty check. I think we could skip that. WDYT?

[rich7420]

sure!