add end-to-end testing setup with Playwright and initial test cases

e2e/playwright.config.js

@@ -0,0 +1,32 @@
+import { defineConfig, devices } from '@playwright/test'
+
+// When frontend and backend are the same origin (embedded binary) set E2E_BASE_URL.
+// For dev, set E2E_FRONTEND_URL (default 5173) and E2E_API_URL (default 2021) separately.
+const FRONTEND_URL =
+  process.env.E2E_FRONTEND_URL ||
+  process.env.E2E_BASE_URL ||
+  'http://localhost:5173'
+
+export default defineConfig({
+  testDir: './tests',
+  timeout: 30_000,
+  retries: process.env.CI ? 2 : 0,
+  workers: 1, // sequential – single SQLite DB
+  reporter: process.env.CI ? 'github' : 'list',
+
+  use: {
+    baseURL: FRONTEND_URL,
+    headless: true,
+    trace: 'on-first-retry',
+    screenshot: 'only-on-failure',
+  },
+
+  globalSetup: './global-setup.js',
+
+  projects: [
+    {
+      name: 'chromium',
+      use: { ...devices['Desktop Chrome'] },
+    },
+  ],
+})