FX.126 Website: a language picker in the footer that sets the language the apps open in (lab only)

Asked on Discord (a Discord member, 2026-11-07): getcadcraft.com has no display-language option. Built: core/components/site-lang.inc in the footer, POST api/site-lang (CSRF, can_lab() else 404) → Lang::rememberChoice writes the same cc_lang cookie the apps read; choices = every shell language file (Lang::siteChoices, 74). Says plainly that the site's own pages stay English for now and that Studio keeps its own choice. Lab and staff only until the owner's go. Translating the site's pages themselves is a separate, larger decision (docs/LANG.md: the site stays English).