Support filtering by operating system

It would be really useful if Atuin allowed filtering by operating system. For example I regularly run into situations where I want to use a macOS-specific command that I don't quite remember, but trying to search for it returns a lot of Linux results from my personal machines. Host-specific search isn't quite adequate here since my work Mac may have been replaced, and so the hostname will be different. Especially with how the GNU and BSD tools are often different in subtle ways it would be helpful if Atuin could only return results that are guaranteed to work on the current system.