Gettext Internationalization

Canonical FP bar: docs/fcis-engineering-rules.md — Functional Core, Imperative Shell: pure domain modules; side effects at edges. HTTP/email/i18n adapters are edges; keep request building and response mapping pure where possible.

End-to-End Workflow

1. Add Gettext calls — wrap strings with gettext/1, dgettext/2, or ngettext/3 in templates, LiveView, and controllers
2. Extract strings — run mix gettext.extract --merge to generate/update .pot and .po files
3. Verify .po files — confirm new msgid entries appear with empty msgstr values
4. Add translations — fill in msgstr values for each target locale
5. Set locale per request — configure a plug or LiveView mount to call Gettext.put_locale/2
6. Test — assert translated strings appear when locale is set

RULES — Follow these with no exceptions