feat(mobile): Add internationalization (i18n) support

[bvisible]

Summary

• Add i18next and react-i18next for translation management in the mobile app
• Create English (en.json) and French (fr.json) locale files with all user-facing strings
• Replace all hardcoded user-facing strings with translation keys across the entire mobile app
• Add language selector in profile settings allowing users to switch between languages
• Configure i18n with automatic language detection and persistence

Changes

This PR introduces full internationalization support for the Raven mobile app, allowing users to use the app in their preferred language. All user-facing text (buttons, labels, messages, error texts, menu items, etc.) has been wrapped with the translation function and corresponding translation keys have been added to the locale files.

Test plan

• Verify all text displays correctly in English (default)
• Switch language to French in settings and verify all text is translated
• Check that language preference persists after app restart
• Verify interpolated strings (with variables) display correctly
• Test error messages and toast notifications are translated

[nikkothari22]

@bvisible The translation strings here make it much more harder to manage. We would add translations similar to how Frappe offers them on the web. That would also remove duplicate translation files (one for mobile, the other for web).

Example: t('media.cameraPermissionDenied') this is very hard to maintain over such a large codebase - and introduces a new paradigm for mobile - hence duplicating work. We would use the way Frappe does it - _("Camera permission not granted")) will get translated based on the user's language selection. Will also find a way to auto-migrate the .po files into the mobile app.

[nikkothari22]

@barredterra Thoughts?

[barredterra]

Having JSON in addition to .po files seems wasteful/duplicative. Can't i18next handle .po files?

[bvisible]

Refactored i18n to Frappe-style with single .po source

Based on the feedback, I've refactored the i18n implementation to:

Changes Made

1. Frappe-style translation syntax

   • Replaced t('key.subkey') with __("English text")
   • Same pattern as Frappe web: _("String to translate")

2. Single source of truth

   • All translations now live in raven/locale/fr.po
   • No duplicate JSON files - .po is converted to JSON at build time
   • Can be used with bench compile-po-to-mo for Frappe integration

3. Build pipeline

   • yarn start automatically runs po-to-json.js
   • Converts .po → JSON for i18next consumption
   • sync-po-with-code.js extracts all strings from components

Architecture

raven/locale/fr.po           ← Single source (edit here)
       ↓ (prestart script)
apps/mobile/locales/*.json   ← Auto-generated (don't edit)

Stats

• 335 French translations preserved
• 123 component files migrated
• Full app re-render on language change

This should address the concerns about:

• ✅ Duplicate translation files
• ✅ Hard-to-maintain t('key.subkey') pattern
• ✅ Frappe compatibility