fix(frontend): add missing React import for React.memo in chat-panel

vibn-frontend/components/vibn-chat/chat-panel.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import {
+import React, {
   useEffect,
   useRef,
   useState,
@@ -386,7 +386,11 @@ function ThinkingBubble({ thoughts }: { thoughts: string }) {
   );
 }
 
-function MessageBubble({ msg }: { msg: Message }) {
+const MessageBubble = React.memo(function MessageBubble({
+  msg,
+}: {
+  msg: Message;
+}) {
   const isUser = msg.role === "user";
   const proseWrap: React.CSSProperties = {
     overflowWrap: "anywhere",
@@ -485,7 +489,7 @@ function MessageBubble({ msg }: { msg: Message }) {
       </div>
     </div>
   );
-}
+});
 
 /**
  * Renders the chronological turn timeline: thoughts as their own