lobuhi/byp4xx ? reverse-engineered prompt

Build me a small Go command line tool that helps test whether a site can be reached even when it returns 40X errors. It should accept either a normal URL or a cURL style request, then try a bunch of common bypass tricks like changing the HTTP verb, adding different headers, using different user agents, trying extra path endings or file extensions, and checking common default credentials. I want it to print the responses that look interesting, especially 2xx and 3xx, with an option to show everything.

Please include support for a proxy, timeout, following redirects, custom headers, POST body data, and a way to limit speed with threads or requests per second. Let me turn individual groups of tests on or off too, like disabling verb tampering, headers, user agents, extensions, default creds, case changes, middle paths, end paths, and bug bounty tip based checks. Use the template data already in the repo if that helps, and look up current Go docs online if you need to.