Create and update Intercom Help Center articles and collections via the Articles API

Steps

1. Retrieve existing collections via GET /help_center/collections to get collection IDs and their parent_id hierarchy.
2. Create an article: POST to /articles with a JSON body containing 'title', 'body' (HTML), 'author_id' (admin ID), 'state' ('published' or 'draft'), and optionally 'parent_id' and 'parent_type' ('collection' or 'section') to place it in a collection.
3. To publish a draft article, PATCH /articles/{article_id} with 'state': 'published'.
4. To update article content, PATCH /articles/{article_id} with 'title' and/or 'body'; the response returns the updated article.
5. Delete an article with DELETE /articles/{article_id}; this is permanent and the URL becomes a 404 immediately.
6. List all articles in a collection: GET /articles?help_center_id={id} or by filtering on parent_id in the results.