W5 release workflow: reintroduce x86_64-apple-darwin (macos-13) for tag-push artefact builds

[liam-ai-reality]

Tracking item for W5 (issue #5) of the v0.1 build.

Context

PR #8 (W1) originally ran x86_64-apple-darwin on the macos-13 GitHub-hosted runner as part of the per-PR cross-platform-build matrix in .github/workflows/ci.yml. That runner has hit recent capacity constraints on the GitHub-hosted fleet, gating PRs behind a queue.

design.md §9's release pipeline is described as on tag push, not on PR:

GitHub Actions matrix on tag push: build per-platform binary, upload artifact, then a publish job downloads all artifacts, stages them into the npm sub-packages and the PyPI wheel directories, and publishes in order: per-platform npm packages → main npm package → PyPI wheels → cargo publish → GitHub Release.

So per-PR cross-platform builds are belt-and-suspenders, not a release-correctness mechanism.

Decision

Drop x86_64-apple-darwin from the per-PR matrix in PR #8. Honour the v0.1 platform commitment by reintroducing it in the W5 release workflow (built at tag push only).

What W5 must include

• A release.yml (or equivalent) workflow that runs the full 5-platform matrix on tag push: aarch64-apple-darwin, x86_64-apple-darwin (macos-13), x86_64-unknown-linux-gnu, aarch64-unknown-linux-gnu, x86_64-pc-windows-msvc.
• Each job uploads its release binary as an artefact.
• A publish job stages artefacts into the npm sub-packages and PyPI wheel directories per design §9, then publishes in the documented order.
• If macos-13 is sunset by GitHub Actions before v0.1 ships, swap to a self-hosted Intel-Mac runner or whatever GitHub's then-current Intel-Mac fleet name is — or formally drop x86_64-apple-darwin from the v0.1 platform matrix (with an explicit roadmap update).

Related

• Closes the gap introduced by the matrix removal in PR v0.1 W1: workspace skeleton + klasp-core types and traits #8.
• W5 tracker: [v0.1 W5] Distribution wiring (npm shim + maturin + GitHub Actions release) #5.