Replace manual state management with TanStack Query (React Query) for more robust server state handling. This refactoring introduces:
- New hooks for queries: useSessions, useSession, useMessages, useMachines
- New hooks for mutations: useSendMessage, useSessionActions, useSpawnSession
- Centralized query client with optimized configuration (5s staleTime, disabled window focus refetch)
- Query key factory for consistent cache invalidation
- Improved message synchronization via socket events with cache updates
- Optimistic updates for message sending with retry capability
- Simplified App.tsx by removing manual state management logic
- Integrated React Query devtools in development mode
This enables automatic cache management, better error handling, and a foundation for more sophisticated data fetching patterns.
