ci: update pinned actions/checkout for Node.js 24

[RomeoRaven]

Context

ONEScripts CI currently pins actions/checkout v4.2.2 by full commit SHA in .github/workflows/ci.yml:16:

uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2

GitHub now warns that this action targets Node.js 20 and is being forcibly run on Node.js 24.

This is maintenance, not a current release blocker: both the post-merge master CI and the v2.1.0 tag CI completed successfully.

Evidence:

• Master CI: https://github.com/RomeoRaven/ONEScripts/actions/runs/30163733317
• v2.1.0 tag CI: https://github.com/RomeoRaven/ONEScripts/actions/runs/30163779948

Follow-up

Update checkout to the current official Node.js 24-compatible release while preserving supply-chain and credential controls.

Acceptance criteria

• Confirm the current official Node.js 24-compatible actions/checkout release.
• Pin it by immutable full commit SHA and retain the readable version comment.
• Preserve persist-credentials: false and permissions: contents: read.
• Full behavioral tests and pinned ShellCheck pass locally and in GitHub Actions.
• The Node.js 20 deprecation annotation is absent from the resulting CI run.