ci: run the publish job on Node 24

[bilby91]

Problem

The publish job has been failing for every commit since npm 12 shipped, so no release — stable or prerelease — can go out. It first surfaced on the run chained off #7's merge (run 32138453942):

npm error code EBADENGINE
npm error notsup Not compatible with your version of node/npm: npm@12.0.2
npm error notsup Required: {"node":"^22.22.2 || ^24.15.0 || >=26.0.0"}
npm error notsup Actual:   {"npm":"10.8.2","node":"v20.20.2"}

actions/setup-node pins node-version: '20', then the next step runs npm install -g npm@latest to reach the npm ≥ 11.5.1 that OIDC trusted publishing needs. npm 12 dropped Node 20, so the two steps now contradict each other. Nothing about the repo changed — the last successful publish was 0.4.5 in June, before npm 12.

Change

Move the pin to Node 24, which npm@latest supports, and note the constraint next to it so the next drift is easier to spot.

ci is unaffected (it uses Bun, not this Node setup).

Verification

Cannot be verified before merge: publish only triggers on a tag push or on a completed ci run on main, so it will not run from a PR branch. The failure mode is a hard engine check with an explicit supported range, and Node 24 sits inside it.

After merge, the CI run on main should chain into a successful publish of a 0.4.5-next.<N>.g<sha> prerelease under the next dist-tag.

🤖 Generated with Claude Code