feat(studio/articles): show drafting_model (LLM used for draft)

Adds drafting_model to the article type and surfaces it in the detail sheet
(provider / model line + raw JSON block). Regenerates admin API types.

src/api/types.ts

@@ -132,6 +132,8 @@ export interface StudioArticle {
   inline_images: Array<{ url: string; alt?: string | null }> | null
   inline_image_prompts: unknown[] | null
   status: ArticleStatus
+  /** LLM used to draft the body, e.g. { provider, model, params }. */
+  drafting_model: { provider?: string; model?: string; [k: string]: unknown } | null
   publish_schedule: Record<string, unknown> | null
   dimzou_document_id: number | null
   dimzou_publication_id: number | null