feat(chat): created basic chat layout

src/components/ui/ChatLayout.jsx

@@ -0,0 +1,34 @@
+import React, { useState } from "react";
+import ChatHeader from "./ChatHeader";
+import ChatWindow from "./ChatWindow";
+import MessageInput from "./MessageInput";
+
+export default function ChatLayout() {
+  const [messages, setMessages] = useState([
+    {
+      role: "assistant",
+      content: "Hello — I can help you with code, explanations, and more.",
+    },
+  ]);
+
+  function handleSend(text) {
+    const userMsg = { role: "user", content: text };
+    setMessages((s) => [...s, userMsg]);
+
+    // fake assistant reply after short delay
+    setTimeout(() => {
+      setMessages((s) => [
+        ...s,
+        { role: "assistant", content: `You said: ${text}` },
+      ]);
+    }, 600);
+  }
+
+  return (
+    <div className="flex flex-col h-[80vh] w-full max-w-3xl mx-auto rounded-lg overflow-hidden shadow-lg border border-slate-700">
+      <ChatHeader />
+      <ChatWindow messages={messages} />
+      <MessageInput onSend={handleSend} />
+    </div>
+  );
+}