📝 Sync v3 docs and content across all nine languages

New shortcode sections, landing layout docs, agent skill sections,
v2→v3 upgrade instructions, translated homepages, and sample
article feature images.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

exampleSite/content/samples/_index.de.md

@@ -5,7 +5,6 @@ description: "Sehen Sie, was mit Blowfish möglich ist."
 cascade:
   showEdit: false
   showSummary: false
-  hideFeatureImage: true
   invertPagination: true
 ---