Publish from a GitHub-hosted runner, and say why

[pathscale]

Unblocks the 0.2.2 release. My change in #16 broke it, and this is the revert plus the reason.

What happened

Moving the two publish jobs to Ubicloud looked like closing a gap — every other job in the repository is on Ubicloud, and nothing about downloading a tarball and running npm publish wants a particular runner. That reasoning was wrong.

npm signs a provenance statement on publish, and the registry refuses one signed anywhere it reads as self-hosted, which is what an Ubicloud runner is:

npm error 422 Unprocessable Entity - PUT https://registry.npmjs.org/solid-layouts
npm error Error verifying sigstore provenance bundle: Unsupported GitHub Actions runner
environment: "self-hosted". Only "github-hosted" runners are supported when publishing
with provenance.

It fails at the registry, not at the runner, so nothing before the PUT catches it. The release run decided correctly, packed a correct solid-layouts-0.2.2.tgz, signed it, and then died.

What this does

Both publish jobs move back to ubuntu-latest, each with the constraint written above it so the next reader does not close the same gap again. release-oxc publishes with provenance the same way, so it would have failed the same way on its next release — it just had not run yet.

Everything else stays on Ubicloud. release-oxc's build matrix keeps its separate, already-documented macos-14 exception.

After merging

Nothing was published, and the decider reads npm rather than the diff, so landing this re-runs the same release unchanged and solid-layouts@0.2.2 goes out. No version bump needed — 0.2.2 is already on master from #16.