- Add comprehensive error handling for pong frame transmission
- Improve SSL error diagnostics in ws_send_frame function
- Add connection state validation before sending frames
- Prevent sending frames on broken or NULL connections
- Better handling of SSL write failures with detailed error reporting
- Graceful degradation when pong frames fail to send
- Enhanced debugging for connection stability issues

The server now handles network interruptions and SSL timeouts more gracefully,
preventing premature connection closures during large file transfers.