chore(ci): ignore Playwright artifacts; track UI test lockfile

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: Aitomates

.gitignore

@@ -5,3 +5,9 @@ dist/
 build/
 *.egg-info/
 artifacts/
+
+# Node / Playwright UI test artifacts (tests/ui)
+node_modules/
+playwright-report/
+test-results/
+.playwright/