add playwright e2e tests for onboarding, contact tracker

- install playwright, configure for chromium with vite dev server
- add onboarding flow test: redirect, form fill, navigation to prozess
- add contact tracker test: create contact, verify in list
- fix onboarding form navigating to /onboarding instead of /prozess
- fix date rendering crash in contact list (cast datum to text)
- exclude @electric-sql/pglite from vite optimizeDeps (WASM bundle)
- add test-results/, playwright-report/ to .gitignore

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -11,6 +11,10 @@ dist/
 # Mise local overrides
 .mise.local.toml
 
+# Playwright
+test-results/
+playwright-report/
+
 # Logs
 *.log