fix: update LangGraphAgent import

Author: brandonmcconnell

package.json

@@ -14,7 +14,6 @@
     "postinstall": "npm run install:agent"
   },
   "dependencies": {
-    "@ag-ui/langgraph": "0.0.7",
     "@ai-sdk/openai": "^1.3.24",
     "@copilotkit/react-core": "^1.10.4",
     "@copilotkit/react-textarea": "1.10.4",

src/app/api/copilotkit/route.ts

@@ -4,7 +4,7 @@ import {
   copilotRuntimeNextJSAppRouterEndpoint,
 } from "@copilotkit/runtime";
 
-import { LangGraphAgent } from "@ag-ui/langgraph"
+import { LangGraphAgent } from "@copilotkit/runtime";
 import { NextRequest } from "next/server";
 
 // 1. You can use any service adapter here for multi-agent support. We use