IndependentPanel: Remove redundant remount toggle; rely on key

Drop the renderContent flag and its timeout flip. Rely solely on the
key={sessionId} to trigger remount when switching sessions, reducing
complexity and avoiding duplicated rerenders.

Author: PeterDaveHello

src/pages/IndependentPanel/App.jsx

@@ -25,7 +25,6 @@ function App() {
   const [sessions, setSessions] = useState([])
   const [sessionId, setSessionId] = useState(null)
   const [currentSession, setCurrentSession] = useState(null)
-  const [renderContent, setRenderContent] = useState(false)
   const [searchQuery, setSearchQuery] = useState('')
   const [debouncedQuery, setDebouncedQuery] = useState('')
   const currentPort = useRef(null)
@@ -84,10 +83,6 @@ function App() {
     ;(async () => {
       if (sessions.length > 0) {
         setCurrentSession((await getSession(sessionId)).session)
-        setRenderContent(false)
-        setTimeout(() => {
-          setRenderContent(true)
-        })
       }
     })()
   }, [sessionId])
@@ -305,7 +300,7 @@ function App() {
           </div>
         </div>
         <div className="chat-content">
-          {renderContent && currentSession && currentSession.conversationRecords && (
+          {currentSession && currentSession.conversationRecords && (
             <div
               key={currentSession.sessionId}
               className="chatgptbox-container"