fix(ci): sync yarn.lock and index.js to git after npm release

[Copilot]

After a release, napi version updates the optional dependency versions in package.json and regenerates index.js, but yarn.lock is never updated to match — causing the next CI run to fail with a lockfile mismatch.

Changes

• node-release.yaml: Add yarn install --no-immutable after npm publish (so the new platform packages are resolvable in the registry) and before the commit step, so yarn.lock is refreshed and committed to git alongside the updated package.json and index.js.

Original prompt

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This section details on the original issue you should resolve

<issue_title>CI: automatic release doesn't update npm files</issue_title>
<issue_description>After running an automatic CI release to npm, impit-node won't install in the subsequent CI run, as the package.json and yarn.lock files are not synchronized. We should push the lockfile (as well as the generated changes in index.js) to git on release to prevent this.</issue_description>

<agent_instructions>Fix this, make minimal changes to achieve the goal. use conventional commits for commit messages and PR titles. do not add excessive comments.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes CI: automatic release doesn't update npm files #399

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[barjin]

Merging even with failing CI, the lockfile is regenerated (and therefore CI unblocked) in #398, which will follow soon.