UserlandDotNet/curl-dot-net ? reverse-engineered prompt

Build me a pure .NET library that lets C# developers run curl commands directly in their apps without calling the curl executable.

I want to be able to paste a curl command from API docs or Stack Overflow into code and have it work, including common things like headers, auth, JSON bodies, file uploads, redirects, timeouts, cookies, proxies, and saving responses. Please also include a nicer fluent API for building requests in code, plus a reusable client style API for repeated calls.

Make it feel like a real developer tool with good error messages, solid async support, and a simple way to get started. Add a few practical examples and basic tests so I can see it working with real requests. If you need to check the latest .NET docs or curl behavior details online, go ahead and look them up.