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>

playwright.config.ts

@@ -0,0 +1,13 @@
+import { defineConfig } from "@playwright/test";
+
+export default defineConfig({
+	testDir: "e2e",
+	webServer: {
+		command: "bun dev",
+		port: 5173,
+		reuseExistingServer: true,
+	},
+	use: {
+		baseURL: "http://localhost:5173",
+	},
+});