ci: build and test Node.js sample

[ShuoRen-TT]

Summary

• add a path-filtered GitHub Actions workflow for the Node.js sample
• install dependencies with Node 20 and npm ci
• require npm run build to pass
• run npm test --if-present so current and future Node tests are covered

Why

The repository currently runs pre-commit checks but does not compile or test rest/nodejs. As a result, strict TypeScript errors in the Node.js sample remained undetected across dependency updates.

This workflow adds a focused build gate for changes under rest/nodejs/** without adding work to unrelated sample PRs.

Validation

• workflow YAML parse: passed
• Prettier: passed
• codespell: passed
• exact workflow commands executed with Node 20 on the combined fix(nodejs): align discovery profile registries #123 + fix(nodejs): narrow required route parameters #125 changes:
  • npm ci: passed, 0 vulnerabilities
  • npm run build: passed
  • npm test --if-present: passed, 3/3 tests

Dependencies

This draft depends on #123 and #125. The new build job is expected to fail against the current main branch until both existing Node.js compile failures are merged. The workflow deliberately does not use continue-on-error; after those dependencies land, it becomes the regression gate that prevents the same drift from recurring.

[vishkaty]

Nice — this gives rest/nodejs the CI coverage that #120 proposes for rest/python (integration tests + server boot + happy-path client). I've borrowed this PR's path-filter shape for #120 so the two workflows stay consistent; happy to align on any other conventions that land here.