fix: stop aggressive 2s chat polling, use WebSocket instead

- Add refetchChatMessages + refetchChatConversations to
  refetchAllCrmQueries so WebSocket dashboard.changed events
  cover pilot chat updates
- Reduce background polling from 2s to 30s (fallback only)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/app/composables/usePilotChat.ts

@@ -619,7 +619,7 @@ export function usePilotChat(opts: {
     pilotBackgroundPoll = setInterval(() => {
       if (!opts.authMe.value) return;
       loadPilotMessages().catch(() => {});
-    }, 2000);
+    }, 30_000);
   }
 
   function stopPilotBackgroundPolling() {