fix: ensure node-fetch is available and report errors

package.json

@@ -3,6 +3,9 @@
   "private": true,
   "version": "0.0.0",
   "type": "module",
+  "engines": {
+    "node": ">=18.0.0"
+  },
   "scripts": {
     "dev": "vite",
     "build": "vite build",
@@ -10,6 +13,7 @@
   },
   "dependencies": {
     "@google/genai": "^1.30.0",
+    "node-fetch": "^3.3.2",
     "papaparse": "^5.5.3",
     "react": "^19.2.0",
     "react-dom": "^19.2.0",
@@ -23,4 +27,4 @@
     "typescript": "~5.8.2",
     "vite": "^6.2.0"
   }
-}
+}