ci(actions): bump Node to 24 so jsdom 30 can install

[Endika]

Problem

CI has been failing on #333 (dependabot bumping jsdom 29.1.1 → 30.0.1) since it opened, so auto-merge never completes. All 64 tests pass; the run dies on an unhandled error while starting the vitest worker:

Failed to start forks worker for tests/smoke.test.ts
Caused by: TypeError: webidl.util.markAsUncloneable is not a function
   ❯ node_modules/jsdom/lib/api.js:12:33

jsdom 30 dropped Node 20:

	engines	undici
jsdom@29.1.1	^20.19.0 || ^22.13.0 || >=24.0.0	^7.25.0
jsdom@30.0.1	^22.22.2 || ^24.15.0 || >=26.0.0	^8.9.0

markAsUncloneable comes from worker_threads and does not exist in Node 20, so undici 8 throws as it loads. The log shows several npm warn EBADENGINE immediately before the failure.

Change

node-version: 20 → 24 in both ci.yml and deploy.yml. Node 24 is the current LTS and its latest (24.19.0) satisfies jsdom 30's ^24.15.0.

deploy.yml is included because it also runs npm test, so it would fail the same way once jsdom 30 lands.

Verification

Run locally against a downloaded Node 24.19.0, since a bump should be tested on the version being pinned:

	Node 24.19.0
jsdom 29.1.1 (current main)	12 files, 66 tests pass
jsdom 30.0.1 (what #333 brings)	12 files, 66 tests pass
npm run build with jsdom 30	passes
EBADENGINE warnings	none

Only the workflows are committed — jsdom was bumped locally to test, then package.json and package-lock.json were reverted, since that bump belongs to #333.

Follow-up, not done here

There is no engines field in package.json and no .nvmrc, so nothing warns when the local and CI Node versions diverge. Adding either would have caught this before dependabot did.