fix(chat): re-attach scroll listener once container mounts

The scroll effect's empty dep array meant it ran only on the first
render, when `chatConfig` is still loading and the component returns
`<ChatLoadingState />` — so `messagesContainerRef.current` was null and
the listener was never attached. Depend on the gating conditions that
control which tree renders, so the effect re-runs once the real
container is in the DOM (and re-attaches when toggling in/out of voice
mode).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: waleedlatif1

apps/sim/app/chat/[identifier]/chat.tsx

@@ -184,7 +184,7 @@ export default function ChatClient({ identifier }: { identifier: string }) {
 
     container.addEventListener('scroll', handleScroll, { passive: true })
     return () => container.removeEventListener('scroll', handleScroll)
-  }, [])
+  }, [chatConfig, isVoiceFirstMode, authRequired])
 
   useEffect(() => {
     if (isStreamingResponse) {