Hardcoded panel texts and venn labels are now stored as structured
frontmatter in content/_index.md and content/_index.de.md, enabling
metadata-backend-driven content updates without template changes.
i18n files now contain only UI labels, not page content.
Animation coupling between template IDs and JS triggers is documented
inline in layouts/index.html.
Also: remove explicit body padding override that was making homepage
nav inconsistent with the rest of the site.
