- Renamed `logmsg` function to `log_event` for consistency with new logging format
- Added ISO 8601 timestamp buffer `timebuf` and replaced `tbuf` with it in log output
- Updated join/leave log messages to include client host and structured format (e.g., "user joined: <nick> (<host>) joined channel <name>")
- Moved leave log call inside the member removal loop to ensure it fires only on actual removal
