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>

package.json

@@ -33,6 +33,7 @@
 	},
 	"devDependencies": {
 		"@biomejs/biome": "^2.4.6",
+		"@playwright/test": "^1.58.2",
 		"@testing-library/jest-dom": "^6.9.1",
 		"@testing-library/react": "^16.3.2",
 		"@types/node": "^25.4.0",