feat: implement basic web app

frontend/src/app/workspace/threads/[thread_id]/page.tsx

@@ -0,0 +1,26 @@
+"use client";
+
+import { useStream } from "@langchain/langgraph-sdk/react";
+import { useParams } from "next/navigation";
+
+import { getLangGraphClient } from "@/core/api";
+import type { MessageThreadState } from "@/core/thread";
+
+const apiClient = getLangGraphClient();
+
+export default function TestPage() {
+  const { thread_id: threadId } = useParams<{ thread_id: string }>();
+  const thread = useStream<MessageThreadState>({
+    client: apiClient,
+    assistantId: "lead_agent",
+    threadId,
+    reconnectOnMount: true,
+    fetchStateHistory: true,
+  });
+  return (
+    <div className="p-4">
+      <div>{threadId}</div>
+      <div>{thread.isLoading ? "loading" : "not loading"}</div>
+    </div>
+  );
+}