Fix cibuildwheel build package shadowing - #465

Summary

• Rename the custom Poetry build hook from build.py to native_build.py so it does not shadow the PyPI build package imported by cibuildwheel
• Include native_build.py in the sdist and update the Poetry build script path
• Bump the package to 0.18.7 for a new publish tag after the failed v0.18.6 tag workflow

Validation

• poetry build
• pytest tests/test_local_deduplication.py -q
• pre-commit run --all-files
• python -c "from build import ProjectBuilder; print(ProjectBuilder.__module__)" prints build._builder from repo root
• python -m cibuildwheel --platform macos --print-build-identifiers starts successfully from repo root

Release note

The pushed v0.18.6 tag points at the commit with the publishing bug, so after merging this fix, publish with a new v0.18.7 tag.

Greptile Summary

• Renames the custom Poetry build hook from build.py to native_build.py so it no longer shadows the PyPI build package.
• Updates pyproject.toml to use and include the renamed build hook in source distributions.
• Refreshes poetry.lock and bumps the package/changelog version to 0.18.7 for the corrected publish workflow.

_{Reviews (2): Last reviewed commit: "Refresh Poetry lockfile" | Re-trigger Greptile}