chore(01-01): install vitest test infrastructure

- Add vitest, @testing-library/react, @testing-library/jest-dom, @testing-library/user-event, jsdom
- Configure vite.config.ts with jsdom test environment and globals
- Add test-setup.ts importing jest-dom matchers

frontend/package.json

@@ -29,6 +29,9 @@
   },
   "devDependencies": {
     "@eslint/js": "^9.39.1",
+    "@testing-library/jest-dom": "^6.9.1",
+    "@testing-library/react": "^16.3.2",
+    "@testing-library/user-event": "^14.6.1",
     "@types/node": "^24.10.1",
     "@types/react": "^19.2.7",
     "@types/react-dom": "^19.2.3",
@@ -37,8 +40,10 @@
     "eslint-plugin-react-hooks": "^7.0.1",
     "eslint-plugin-react-refresh": "^0.4.24",
     "globals": "^16.5.0",
+    "jsdom": "^28.1.0",
     "typescript": "~5.9.3",
     "typescript-eslint": "^8.48.0",
-    "vite": "^7.3.1"
+    "vite": "^7.3.1",
+    "vitest": "^4.0.18"
   }
 }