Use Python to combine verification output

[yrasool]

Change

find_last_output used cat to merge rank CSV files. This now uses Python file I/O, with the existing output order unchanged.

Checks

• python tools/test_verify_output.py
• ruff check tools
• Python compile checks
• codespell on changed files
• local Sphinx build
• GitHub documentation CI
• git diff --check

CMake and C++ unit tests were not run locally because CMake and FleCSI are not installed here.

Closes #15

[AndresYague]

Simple MR that makes the code more portable as it does not require that the system has cat. The code will be slower than running cat but not by a significant enough margin.

It may be useful to provide a buffer length of a few MB to shutil.copyfileobj to handle the 3D case output a bit faster.

[yrasool]

Simple MR that makes the code more portable as it does not require that the system has cat. The code will be slower than running cat but not by a significant enough margin.

It may be useful to provide a buffer length of a few MB to shutil.copyfileobj to handle the 3D case output a bit faster.

Thanks, I added a 1 MiB buffer. In a local 128 MiB 3D-shaped merge, it was 1.34x faster than a 64 KiB buffer. The output test and docs check pass.

[AndresYague]

Thanks, I added a 1 MiB buffer. In a local 128 MiB 3D-shaped merge, it was 1.34x faster than a 64 KiB buffer. The output test and docs check pass.

This all looks good to me!