- Add ReconnectingBanner component to show "Reconnecting..." status
- Track SSE connection state in App.tsx with onDisconnect handler
- Add onBlocked callback to useSendMessage for handling blocked send attempts
- Provide haptic feedback when send is blocked due to no API or session
- Show toast notification when message cannot be sent due to server disconnection
- Add translation keys for reconnecting message and send blocked feedback in en/zh-CN
close#125