lib/blog.js now reads content/blog/<slug>/ (meta.md + fr.md/en.md):
listing shows the requested language with fallback to the first
available one, getBlogPost(slug, lang) reports untranslated posts via
an untranslated field, and the draft/share accessors keep parsing
<slug>-<token> from meta.md. Draft filtering stays keyed on the shared
draftsVisible() rule, now exported from lib/content.

/blog/[slug] renders the default language with an FR/EN switch when a
post exists in both; a new /blog/[slug]/[lang] route serves the other
language (static params only mint languages with content). A missing
language renders an honest banner linking to the one that exists.
yarn post scaffolds the folder shape. Flat collections are untouched.