sanitize-pathname

Sanitize the pathname segment of the URL like a browser does.

This is useful for web frameworks/routers to do before registering a new route so that it matches what the web server will give you (for example, Request.url in Bun/Deno). Here's what it does:

1. Run encodeURIComponent except for %, [, ], !, *, ', (, ), ;, :, @, &, =, +, $, ,, /, ?, #, -
2. Replace all backslashes (\) with forward slashes (/)
3. Add a forward slash at the beginning if there's none
4. Resolve ".." and "." segments