feat(tests): Jest backend (38 tests), Jest RTL frontend (28 tests), Playwright E2E spec

frontend/playwright.config.js

@@ -0,0 +1,14 @@
+const { defineConfig, devices } = require('@playwright/test');
+
+module.exports = defineConfig({
+  testDir: './e2e',
+  timeout: 30000,
+  retries: process.env.CI ? 2 : 0,
+  use: {
+    baseURL: process.env.E2E_BASE_URL || 'http://localhost:52867',
+    trace: 'on-first-retry',
+  },
+  projects: [
+    { name: 'chromium', use: { ...devices['Desktop Chrome'] } },
+  ],
+});