- MessageInput: HTTP fallback when WebSocket not OPEN (prevents silent failures)
- WsClient: add trySend() returning bool to detect WS availability
- Backend: POST /api/messages/chat/:chatId endpoint for HTTP message send
- openOrCreatePrivate: use openChat() for consistency after refreshing chat list
- iOS fix: inputs get font-size:16px on mobile to prevent Safari auto-zoom
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>