… from X-Forwarded-For header

- Added getRealRemoteIP function to retrieve the real client IP address when behind a reverse proxy.
- Updated authentication logging to use the extracted IP instead of r.RemoteAddr.
- Ensured compatibility for both proxy and non-proxy setups, falling back to r.RemoteAddr when X-Forwarded-For is not present.

- Added a section in README.md explaining how to configure Fail2Ban for WebDAV security.
- Included examples for filter and jail configuration.
- Provided instructions on setting up and testing Fail2Ban to block IPs after failed login attempts.

…lume

- Added logging for invalid username attempts to provide more detailed failure reasons.
- Removed "login attempt" log entries to reduce log volume and focus on final verification results.
- Retained logging for invalid password and successful user authorization for clarity.

…code cleaner and more focused