- Dedicated 'Run unit tests' step (npm run test:unit) so unit tests are
visible and guaranteed in CI rather than implied by the build script.
- Build now calls react-scripts build directly, avoiding a redundant
second Jest run (CI=true still fails the build on lint warnings).
- Bump Node 18 (EOL) -> 20 and enable npm dependency caching.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>