The webmail's QR encodes a `bulwarkmail://pair?...` link, but nothing
registered that scheme: scanning it with the system camera or Google
Lens did nothing, and without a camera there was no way in at all.
- `bulwarkmail` is registered in `app.config.js` (iOS) and the committed
AndroidManifest. Links are parked in a small store and picked up by
the sign-in screen, or by "Add account" when already signed in, once
per launch.
- "Paste sign-in link" on the sign-in screen (and next to the server
step's scan hint) takes a link copied from the webmail.
- While pairing, the waiting screen names the webmail being paired with.
- 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.
Linus Rath