✨ enable free-threaded Python 3.14t support

[vanandrew]

Summary

Enables free-threaded (no-GIL) Python 3.14t wheels alongside the standard build matrix, while preserving Ctrl+C interruptibility on regular GIL builds.

Changes

• build.yml: Split cp314* glob into cp314-* (standard) and cp314t* (free-threaded) matrix entries, so each is reported as its own job.
• pyproject.toml: [tool.cibuildwheel].skip now only excludes *musllinux*; cp314t-* is built on every supported OS.
• src/warpkit.cpp: Declared py::mod_gil_not_used() on the module (pybind11 3.0+ syntax) so CPython does not re-enable the GIL when the extension loads under a free-threaded interpreter.
• include/warps.h: Wrapped every PyErr_CheckSignals() site in a new WARPKIT_CHECK_SIGNALS() macro that compiles to a no-op when Py_GIL_DISABLED is defined. GIL builds keep Ctrl+C interruptibility during long ITK operations; the free-threaded build skips the GIL-requiring check.
• CLAUDE.md: Documents the macro and the updated wheel matrix.

Test plan

• All 15 wheel jobs green (3.11 / 3.12 / 3.13 / 3.14 / 3.14t × ubuntu-latest / ubuntu-24.04-arm / macos-latest)
• PyInstaller bundles green on linux-x86_64, linux-aarch64, macos-arm64
• Docker linux/amd64 + linux/arm64 builds green
• codecov patch + project pass
• Local uv run pytest -q (210 passed), uvx ruff check, uvx ruff format --check, uvx pyright clean

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.71%. Comparing base (0a5377f) to head (16845c9).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #23   +/-   ##
=======================================
  Coverage   94.71%   94.71%           
=======================================
  Files          16       16           
  Lines        1249     1249           
=======================================
  Hits         1183     1183           
  Misses         66       66           

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[Copilot]

Pull request overview

This PR adds CI coverage for Python 3.14 free-threaded (“no-GIL”) builds by splitting the wheel build matrix into standard cp314-* and free-threaded cp314t*, and updating the extension code/config to better tolerate no-GIL builds.

Changes:

• Update GitHub Actions wheel matrix to build/test both cp314-* and cp314t* wheels.
• Enable cp314t-* builds in cibuildwheel by removing them from the skip list.
• Adjust the C++ extension for free-threaded builds by declaring py::mod_gil_not_used() and guarding PyErr_CheckSignals() behind a macro that becomes a no-op under Py_GIL_DISABLED.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/warpkit.cpp	Declares the module as mod_gil_not_used() to opt into free-threaded behavior.
include/warps.h	Introduces WARPKIT_CHECK_SIGNALS() to avoid PyErr_CheckSignals() under Py_GIL_DISABLED.
pyproject.toml	Removes cp314t-* from cibuildwheel’s skip list so free-threaded wheels can build.
.github/workflows/build.yml	Splits Python 3.14 builds into cp314-* and cp314t* matrix entries.
CLAUDE.md	Updates CI documentation to reflect free-threaded wheel support and the new signal-check behavior.

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