Create an article (draft) from a pre-built outline

Create a draft article from an outline you ALREADY have. This does NOT generate the body content, and it cannot invent the outline for you: articleOutline is required and its generateOutlineResponse must be the whole object returned by generate_outline. For a fully AI-written article, prefer generate_article, which produces the outline and the content in one call. Use this only for the step-by-step wizard, where the user reviews the outline first; then call start_article_generation with the returned slug to write the content.