feat: scoped api with token authentication

Hi,

I would like to have an easy, documented, scoped read-only (?) REST api to access using token authentication.

My primary usecase would be to display my current overtime credits in my statusbar.

So an endpoint like /user/credits with the token as request header and a response like:

[
  "user": {
       "peterm": {
          "credits": 100
        }
    },
]

[c0rydoras]

i'm not sure how realistic implementing this is, what do you thing? @adfinis/dev-backend