Set up CI Pipeline (GitHub Actions)

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DevOps Description: Automate testing to ensure regression safety. Tests should run automatically on every Pull Request and push to the main branch.

Tasks:

Create workflow file .github/workflows/test.yml.

Define jobs: checkout code, setup Node.js, install dependencies (npm ci), run tests.

Acceptance Criteria (DoD):

[x] Tests run automatically on new PRs.

[x] GitHub reports "Success" or "Failure" status for commits.