ui-visual-validator

CI/CD visual regression setup and pre-commit visual verification checklist. Scoped complement to reality-checker agent — adds: visual regression tool ecosystem (Chromatic, Percy, Applitools, BackstopJS, Playwright Visual), 13-item mandatory verification checklist, and GitHub Actions screenshot diff pipelines. Use when setting up automated visual regression tests in CI/CD or running systematic pre-PR visual verification beyond what reality-checker provides.