fix: Track Cython inputs for editable pixi-build-python builds (generated by Codex)

[kkraus14]

Track Cython inputs for editable pixi-build-python builds

Generated by Codex.

Summary

• keep pure Python sources excluded from editable pixi-build-python input globs
• include Cython inputs (.pyx, .pxd, .pxi) only when Cython is declared in the model dependencies or build-system.requires
• use those Cython inputs to invalidate the source artifact cache when compiled editable builds change
• update input-glob snapshots

Fixes #6122.

Tests

pixi run -e rust-test insta test -p pixi-build-python --accept -- input_globs
pixi run -e rust-test insta test -p pixi-build-python --check -- input_globs
pixi run -e rust-test cargo build -p pixi-build-python

Manual reproducer check:

• built the patched pixi-build-python backend locally
• ran the issue Editable pixi-build-python Cython source package is not rebuilt after Cython input changes #6122 reproducer with PIXI_BUILD_BACKEND_OVERRIDE
• confirmed the source artifact sidecar records repro.pyx
• changed the Cython docstring from v3 to v4
• confirmed pixi run show-doc rebuilt and printed v4
• confirmed a second unchanged pixi run show-doc printed v4 without rebuild output

[kkraus14]

Also happy to just add these into the existing python_globs if you feel it's more appropriate

[baszalmstra]

Would it be possible to add these only if cython is a dependency? Tracking globs has an overhead, seems wasteful to always add these if they will not match anyway.

[kkraus14]

Addressed the review comment: Cython input globs are now added only when Cython is present in the model dependencies or in build-system.requires.

I also added tests for explicit model dependency, pyproject build-system dependency, and the no-Cython case.

Generated by Codex.

[kkraus14]

Would it be possible to add these only if cython is a dependency? Tracking globs has an overhead, seems wasteful to always add these if they will not match anyway.

We were previously always tracking .pyx Cython files where this PR adds tracking .pxd and .pxi files as well, but happy to move all of them to only be tracked in the case of Cython being a dependency. This would be a change in behavior if someone is doing something funky where they're getting Cython outside of pixi's dependency system.