test: add e2e tests

frontend/e2e/auth.setup.ts

@@ -0,0 +1,23 @@
+import { test as setup } from '@playwright/test';
+import path from 'path';
+
+const authFile = path.join(__dirname, '.auth/user.json');
+
+/**
+ * Logs in once and saves the session cookie so all E2E tests can reuse it.
+ * Configure credentials via environment variables:
+ *   E2E_USERNAME  (default: admin)
+ *   E2E_PASSWORD  (default: admin)
+ */
+setup('authenticate', async ({ page }) => {
+	const username = process.env.E2E_USERNAME ?? 'admin';
+	const password = process.env.E2E_PASSWORD ?? 'admin';
+
+	await page.goto('/login');
+	await page.getByLabel('Benutzername').fill(username);
+	await page.getByLabel('Passwort').fill(password);
+	await page.getByRole('button', { name: 'Anmelden' }).click();
+	await page.waitForURL('/');
+
+	await page.context().storageState({ path: authFile });
+});