This update has been tested on Paper Spigot 1.17.1. Custom recipes, modifying vanilla recipes, permissions are all working in my tests.

I fixed an issue preventing the recipe result menu from accepting item, and I made the recipe permissions work with smithing recipes. Some other recipe types are difficult to implement permissions for due to the way they're designed, but I'm working on it.

Also added recipe permission to recipes in the list menu so you know what perm to add / remove to restrict access to that recipe.