[FEATURE] nginx Community NTLM Plugin

### What's needed and why?

Hi Simon,

It would be really nice and competitive to Support Ntlm passthrough Like forks of NPM. Especially for Exchange on prem this Feature is Mandatory.

See here - https://github.com/gabihodoroaga/nginx-ntlm-module

And fork of npm : https://github.com/greetoz/nginx-proxy-manager

This would be a game changer … and quite competitive

### Implementations ideas (optional)

_No response_

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct

Start by reviewing the referenced nginx-ntlm-module and the nginx-proxy-manager fork to understand the requested NTLM passthrough behavior. Then locate how BunkerWeb configures and extends nginx, and define tests for Exchange or other NTLM upstream traffic. Done means documented, working NTLM passthrough support with regression coverage.

Written by the indexing model from the issue text.