chore(06-01): mark test-kotlin-syntax articles as draft (FR + EN)

- Add `draft: true` to frontmatter of both test-kotlin-syntax.md files
  so they are excluded from all `queryCollection(...).where('draft', '=', false)`
  listings (D-14).
- Articles remain accessible via direct URL (no draft filter on `.path(x).first()`),
  keeping them available for internal rendering tests.
- Listings will be empty until real Hytale seed articles land in Phase 8 —
  the empty state will render per D-16 ("Hytale articles coming soon" CTA).
- Body content untouched (only frontmatter +1 line each).

content/fr/blog/test-kotlin-syntax.md

@@ -3,6 +3,7 @@ title: "Guide du format Markdown"
 description: "Référence complète de tous les éléments et composants disponibles dans les articles"
 date: "2026-04-21"
 tags: ["guide", "markdown", "mdc"]
+draft: true
 ---
 
 ## Typographie de base