chore: import upstream snapshot with attribution

examples/v2/node-express/src/index.ts

@@ -0,0 +1,51 @@
+import express from "express";
+import dotenv from "dotenv";
+import { z } from "zod";
+import {
+  CopilotRuntime,
+  createCopilotEndpointSingleRouteExpress,
+  BuiltInAgent,
+  defineTool,
+  ToolDefinition,
+} from "@copilotkit/runtime/v2";
+
+dotenv.config();
+
+const roastTool = defineTool({
+  name: "sayHello",
+  description: "Say hello while roasting the user's name",
+  parameters: z.object({
+    roast: z.string().describe("A playful roast about the user's name"),
+  }),
+  execute: async ({ roast }) => {
+    console.log(roast);
+    return "The person has been roasted.";
+  },
+}) as unknown as ToolDefinition;
+
+const runtime = new CopilotRuntime({
+  agents: {
+    default: new BuiltInAgent({
+      model: "openai/gpt-4o-mini",
+      tools: [roastTool],
+    }),
+  },
+});
+
+const app = express();
+
+app.use(
+  "/api/copilotkit",
+  createCopilotEndpointSingleRouteExpress({
+    runtime,
+    basePath: "/",
+  }),
+);
+
+const port = Number(process.env.PORT ?? 4000);
+
+app.listen(port, () => {
+  console.log(
+    `CopilotKit v2 runtime listening at http://localhost:${port}/api/copilotkit`,
+  );
+});