feat: implement PI core chat timeline

src/pages/Chat/index.tsx

@@ -1,4 +1,4 @@
-import { OpencodeChatPanel } from './OpencodeChatPanel';
+import { CodingChatPanel } from './CodingChatPanel';
 import { useNavigate } from 'react-router-dom';
 
 function getNavigationDraft(state: unknown): string | undefined {
@@ -22,8 +22,7 @@ export function Chat() {
 
   return (
     <div data-testid="chat-operation-page" className="flex h-[calc(100%_+_3rem)] min-h-0 -m-6 overflow-hidden bg-background">
-      <OpencodeChatPanel
-        variant="main"
+      <CodingChatPanel
         navigationDraft={navigationDraft}
         onOpenProjectSettings={() => navigate('/project-config')}
       />