I only see a categories controller in the public namespace, which most probably suggests to me that you are sending all the categories and articles and their corresponding details in one single API call. That's actually not a good way to create APIs. You should also have a article controller in the public namespace to send the detail of a particular article based on the slug. The categories controller should simply send the bare minimum details of the article like say the title of the article. This API division is required so to ensure that the APIs are performant.
I only see a categories controller in the public namespace, which most probably suggests to me that you are sending all the categories and articles and their corresponding details in one single API call. That's actually not a good way to create APIs. You should also have a article controller in the public namespace to send the detail of a particular article based on the slug. The categories controller should simply send the bare minimum details of the article like say the title of the article. This API division is required so to ensure that the APIs are performant.