add vitest and regression tests for arc 1

package.json

@@ -12,6 +12,8 @@
     "analyze:requests": "node scripts/request-analysis-worker.mjs",
     "validate:content": "node scripts/validate-content-schemas.mjs",
     "build": "tsc -b && vite build",
+    "test": "vitest run",
+    "test:watch": "vitest",
     "lint": "eslint .",
     "preview": "vite preview"
   },
@@ -23,6 +25,9 @@
   },
   "devDependencies": {
     "@eslint/js": "^10.0.1",
+    "@testing-library/jest-dom": "^6.9.1",
+    "@testing-library/react": "^16.3.2",
+    "@testing-library/user-event": "^14.6.1",
     "@types/node": "^24.12.3",
     "@types/react": "^19.2.14",
     "@types/react-dom": "^19.2.3",
@@ -31,9 +36,10 @@
     "eslint-plugin-react-hooks": "^7.1.1",
     "eslint-plugin-react-refresh": "^0.5.2",
     "globals": "^17.6.0",
+    "jsdom": "^29.1.1",
     "typescript": "~6.0.2",
     "typescript-eslint": "^8.59.2",
-    "vite": "^8.0.12"
+    "vite": "^8.0.12",
+    "vitest": "^4.1.9"
   }
 }
-