refactor: remove unused WebSearchToolUI component and update onFetchChart to return a Promise

package.json

@@ -11,9 +11,6 @@
   "dependencies": {
     "@ai-sdk/google": "^1.1.25",
     "@ai-sdk/openai": "^1.2.5",
-    "@assistant-ui/react": "^0.8.6",
-    "@assistant-ui/react-ai-sdk": "^0.8.0",
-    "@assistant-ui/react-markdown": "^0.8.0",
     "@radix-ui/react-scroll-area": "^1.2.3",
     "@radix-ui/react-slot": "^1.1.2",
     "@radix-ui/react-tooltip": "^1.1.8",