test(infra): add E2E Playwright verification spec for Vaultwarden routing

- Verify vault.researchstack.info routes successfully to standalone Vaultwarden container on cupfox

Build: 0 jobs, 0 errors (lake build)

4-Infrastructure/k3s-flake/tests/vaultwarden-verify.spec.ts

@@ -0,0 +1,20 @@
+import { test, expect } from '@playwright/test';
+
+test('Verify Vaultwarden accessible via subdomain', async ({ page }) => {
+  page.on('console', msg => console.log(`Browser Console [${msg.type()}]:`, msg.text()));
+  page.on('requestfailed', req => console.log('Request Failed:', req.url(), req.failure()?.errorText));
+  page.on('pageerror', err => console.log('Page Error:', err.message));
+
+  console.log('Navigating to Vaultwarden via domain...');
+  await page.goto('https://vault.researchstack.info');
+  await page.waitForTimeout(5000);
+
+  console.log('Current URL:', page.url());
+  console.log('Page Title:', await page.title());
+
+  await page.screenshot({ path: '/tmp/vaultwarden-verify-final.png' });
+
+  // Assert that we have landed on the Vaultwarden (Bitwarden Web Vault) main page
+  const title = await page.title();
+  expect(title.toLowerCase()).toContain('vaultwarden');
+});