What's missing from this simple recipe that creates a user?
I'll put in an answer although I'm not 100% sure. I think that you got the permissions wrong on ~/.ssh and it should be 0700 instead of 0600, otherwise the user cannot access it.

Another tip which is unrelated to your problem, the user resource has a property manage_home (https://docs.chef.io/resource_user.html#properties) which will create the home directory for you and will you save a redundant resource.