initial darwin support

[MattSturgeon]

In Defelo/nixpkgs-review-gha#22 I experimented with some basic disk space reclamation for darwin runners: diff

This is based on https://github.com/azuwis/actions/blob/395a1d18d5eb0e2b349f2a887a31996f330307b9/nix/prepare.sh#L57-L80

This can be seen running here: https://github.com/MattSturgeon/nixpkgs-review-gha/actions/runs/16032474545/job/45236209227
and here: https://github.com/MattSturgeon/nixpkgs-review-gha/actions/runs/16032474545/job/45236209224

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I'm wondering if this is something that we should get merged into nothing-but-nix?

At least initially, many of the action's inputs would not be applicable to darwin, and many of the action's features would not be supported. But from a high-level concept perspective, it'd still have the same goal of reclaiming as much space as possible from the default darwin images.

[peterbecich]

Yes please

[peterbecich]

as easy temporary solution can we make this Action a no-op on Mac? https://github.com/haskell/hackage-server/actions/runs/16542665799/job/46786011448?pr=1408

[trueNAHO]

as easy temporary solution can we make this Action a no-op on Mac? https://github.com/haskell/hackage-server/actions/runs/16542665799/job/46786011448?pr=1408

Stylix replicates nothing-but-nix's implementation with

      - uses: wimpysworld/nothing-but-nix@10c936d9e46521bf923f75458e0cbd4fa309300d  # yamllint disable-line rule:line-length
        if: runner.os == 'Linux'

github:nix-community/stylix, /.github/workflows/check.yml

inspired by

• nothing-but-nix/action.yml

  Line 34 in 10c936d

  if [[ "${{ runner.os }}" == "Linux" ]]; then

• nothing-but-nix/action.yml

  Line 357 in 10c936d

  if: ${{ runner.os }} == 'Linux'