CI/CD: Automated testing pipelines

Summary

GitLab CI pipeline to run backend & frontend tests on every push/MR with coverage artifacts.

Scope

• Jobs: backend:test (Jest), frontend:test (Vitest).
• Coverage artifacts (Cobertura/JUnit where supported).
• Pipeline badges optional.

Tasks

• .gitlab-ci.yml with two jobs in stage test.
• Use node:20 images; npm ci; run tests with coverage.
• Upload coverage artifacts.
• Document in README/Wiki.

Acceptance criteria

• Pipelines run automatically on push/MR.
• Failures block merges.
• Coverage artifacts visible in GitLab UI.

Dependencies

• None (but tests depend on implemented features).