Configure Playwright for headless CI and add Gitea workflow with container support

frontend/package.json

@@ -10,10 +10,11 @@
     "react-dom": "^19.2.1"
   },
   "devDependencies": {
+    "@playwright/test": "^1.58.2",
     "@testing-library/jest-dom": "^6.6.0",
     "@testing-library/react": "^16.1.0",
     "@vitejs/plugin-react": "^4.3.0",
-    "jsdom": "^29.0.0",
+    "happy-dom": "^20.8.4",
     "vite": "^6.0.0",
     "vitest": "^3.0.0"
   },
@@ -21,7 +22,8 @@
     "start": "vite",
     "build": "vite build",
     "preview": "vite preview",
-    "test": "vitest"
+    "test": "vitest",
+    "test:e2e": "playwright test"
   },
   "browserslist": {
     "production": [