fix: venv usage

[2bndy5]

related to #305
resolves #313

Python venv fix

Apparently, uv respects the UV_PROJECT_ENVIRONMENT env var for only certain uv commands.

This workaround involves a combination of --project and --directory:

uv run --project $GITHUB_ACTION_PATH --directory (pwd) cpp-linter ...$inputs

Where (pwd) is the nushell builtin command similar to bash's $(pwd) and should point to the working directory.

Tested in a container

I ran this in the test repo using the ubuntu:latest docker image (for Linux runners only).
While it works now (after switching from bash to nushell), I found that the LLVM script requires certain tools that are not present in docker images.

So after a lot of trial and error, I revised the README to describe the required tools for each platform. It turns out nushell's builtin http command uses curl or wget underneath (on Linux).

sudo is no longer required if the docker container runs as root. 🎉

Summary by CodeRabbit

• Documentation

  • Added a “Required tools installed” section with OS-specific prerequisites and install guidance; updated the warning to link to it and added cross-link anchors.
  • Clarified cache-enable description to explain caching behavior, defaults, and cache location.

• Refactor

  • Reworked dependency/setup and linter invocation to a unified, cross-platform flow (nu-based + uv) with verbosity/debug handling; public inputs/outputs unchanged.

• Chores

  • Bumped internal tool versions and improved installer reliability.