The vendored catalogs were last synced on 2026-08-29 and had fallen
about a hundred keys behind, including the German update and the
translations of `email_viewer.forward_as_attachment`.
- re-vendor all 27 `locales/<lang>/common.json` from webmail e33ab899
- drop the overlay's `email_composer.send_failed`, which the webmail
catalog now carries with translations
- keep 15 keys the webmail renamed or dropped but the app still uses,
moved into `locales/rn/en.json` by `npm run i18n:harvest`
- Implemented ContentSendersSettings component for managing trusted senders.
- Added LanguageSettings component to allow users to select their preferred language.
- Introduced minimal i18n support with locale detection and translation functions.
- Created a locale store using Zustand for managing locale state and persistence with AsyncStorage.
- Added a script to sync locale JSON files from the parent webmail repository.