fix: point cuda_bindings sdist build at local cuda_pathfinder wheel

cuda_bindings build backend imports cuda.pathfinder, so pip's build
isolation needs to find the locally-built cuda_pathfinder wheel
instead of pulling from PyPI. Set PIP_FIND_LINKS to the pathfinder
dist directory.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: cpcloud

.github/workflows/test-sdist.yml

@@ -84,6 +84,7 @@ jobs:
           export CUDA_PYTHON_PARALLEL_LEVEL=$(nproc)
           export CC="sccache cc"
           export CXX="sccache c++"
+          export PIP_FIND_LINKS="$(pwd)/cuda_pathfinder/dist"
           python -m build --sdist cuda_bindings/
           pip wheel --no-deps --wheel-dir cuda_bindings/dist cuda_bindings/dist/*.tar.gz