fix: type

packages/server/src/handlers/chat.ts

+import type { ChatMessage } from "@llamaindex/core/llms";
 import { type Message } from "ai";
 import { IncomingMessage, ServerResponse } from "http";
-import { type ChatMessage } from "llamaindex";
 import type { WorkflowFactory } from "../types";
 import {
   parseRequestBody,