Downgrade to stable Vite 5.x and React 18.x for Vercel compatibility

frontend/package.json

@@ -10,22 +10,22 @@
     "preview": "vite preview"
   },
   "dependencies": {
-    "axios": "^1.15.0",
-    "react": "^19.2.4",
-    "react-dom": "^19.2.4"
+    "axios": "^1.7.9",
+    "react": "^18.3.1",
+    "react-dom": "^18.3.1"
   },
   "devDependencies": {
     "@eslint/js": "^9.39.4",
     "@types/node": "^24.12.2",
     "@types/react": "^19.2.14",
     "@types/react-dom": "^19.2.3",
-    "@vitejs/plugin-react": "^6.0.1",
+    "@vitejs/plugin-react": "^4.3.4",
     "eslint": "^9.39.4",
     "eslint-plugin-react-hooks": "^7.0.1",
     "eslint-plugin-react-refresh": "^0.5.2",
     "globals": "^17.4.0",
-    "typescript": "~6.0.2",
+    "typescript": "^5.6.3",
     "typescript-eslint": "^8.58.0",
-    "vite": "^8.0.4"
+    "vite": "^5.4.11"
   }
 }