This endpoint performs an upsert operation: it creates a new article or updates an existing one
based on the article_id you provide.

Article Identification

If article_id is provided:

• The article with that ID will be updated
• If the article doesn't exist, a 404 error will be returned

If article_id is not provided:

• A new article will be created
• The slug must be unique within the specified collection

Automatic Synchronization (when updating)

When updating an existing article, the system automatically handles important synchronization tasks:

1. Collection Move: When you change collection_id, if this article has linked
versions in other locales, they will be automatically moved to the corresponding
collections in their respective locales. This ensures your article organization
remains consistent across all languages.

2. Featured Status Sync: When you change is_featured, the new value is automatically
synchronized across all linked articles in other locales. This ensures featured
articles are highlighted consistently regardless of language.

Required Fields

• collection_id: The collection where the article belongs (required)
• title: Article title (required)
• body: Article content, supports HTML (required)
• slug: URL-friendly identifier, must be unique within the collection (required)
• status: Publication status - draft or published (required)
• written_by: Account ID from /writers endpoint (required)

Optional Fields

• article_id: ID for updating an existing article (optional)
• description: Article description (optional)
• keywords: Array of search keywords (optional)
• is_featured: Whether article is featured, synced across linked articles (optional, default: false)
• is_ai_enabled: Enable AI training for this article (optional, default: false)

The body HTML is automatically processed and sanitized. The slug must remain unique
within the target collection.

Content Visibility

Use contact_segment_ids and company_segment_ids to restrict access to this article in two contexts:

• Aura (AI assistant): only contacts/companies in those segments can interact with this content.
• Help Center: if the help center is published, only contacts/companies in those segments will see
  this article in the public help center.

If an article has no explicit visibility rules, it inherits them from its parent collection (if any).

• Omit the field (or pass null) to leave existing visibilities unchanged.
• Pass an empty array [] to remove all visibility restrictions for that segment type.
• Pass a non-empty array to replace the current visibilities with exactly those segment IDs.

Requires the content_visibility feature on your plan.