Fix i18n implementation by updating translation routes and service to use correct export functions

[kWeglinski]

This PR fixes the i18n implementation by making the following changes:

1. Updated translationRoutes.js:

   • Modified the /:lang/:namespace route to use getNamespaceTranslations() instead of readTranslations()
   • Updated the POST route to use proper translation structure
   • Fixed error handling in both routes

2. Updated translationService.js:

   • Added writeTranslations to the exports so it can be used in translationRoutes.js

3. Added new i18n functionality:

   • Created LanguageSwitcher component
   • Implemented translation backend with i18next
   • Added initial translations for English and Spanish

4. Key Changes Made:

   • Replaced direct file access with proper service functions
   • Improved error handling and response structure
   • Fixed translation data structure to be more consistent

5. Testing:

   • All tests are passing (15/15)
   • The server starts successfully on port 3002

The implementation now properly uses the export functions from translationService.js and has a more consistent approach to handling translations. The server is working correctly as evidenced by the passing tests.