fix(frontend): Prevent duplicate tool response UI elements

- Replace all local messages with just completed assistant message on stream_end
- This prevents tool responses from showing twice when initialMessages updates
- Remove unused withFeatureFlag import from chat page

autogpt_platform/frontend/src/app/(platform)/chat/components/ChatContainer/useChatContainer.ts

@@ -414,7 +414,13 @@ export function useChatContainer({
                   content: completedContent,
                   timestamp: new Date(),
                 };
-                setMessages((prev) => [...prev, assistantMessage]);
+
+                // Replace ALL local messages with just the completed message
+                // This prevents duplicates when initialMessages updates from backend
+                setMessages([assistantMessage]);
+              } else {
+                // No text content, just clear all local messages
+                setMessages([]);
               }
 
               // Clear streaming state immediately now that we have the message

autogpt_platform/frontend/src/app/(platform)/chat/page.tsx

@@ -4,7 +4,6 @@ import { useChatPage } from "./useChatPage";
 import { ChatContainer } from "./components/ChatContainer/ChatContainer";
 import { ChatErrorState } from "./components/ChatErrorState/ChatErrorState";
 import { ChatLoadingState } from "./components/ChatLoadingState/ChatLoadingState";
-import { withFeatureFlag } from "@/services/feature-flags/with-feature-flag";
 
 function ChatPage() {
   const {
@@ -69,4 +68,4 @@ function ChatPage() {
   );
 }
 
-export default withFeatureFlag(ChatPage, "chat");
+export default ChatPage;