How am I supposed to use an API that requires OAuth for an app that shouldn't let the user log in?

Rough plan: I want to make an app that displays a virtual pc keyboard. When you click on a specific key, you can search for a term. This search goes out to an API call. I then want to receive the result and do stuff with it. If it helps: Its meant for planning keybinds for world of warcraft.

The battle.net API requires OAuth so I get an access token and use it for the API calls I mentioned.

But I don't want users to log in to my app with their battle.net account. So I have to generate that access token somewhere else. I thought of a small nodejs service that authenticates with my clientID and clientsecret ... but I'm not sure how to get the access key then. OAuth does always mean I have to grant my nodejs service access manually, right?

How am I supposed to set up such a project?