feat: add Greek language support

- Added 'el-GR' locale to the client-side locales array
- Included 'el-GR' in the server-side LANGUAGES constant
- Updated i18n configuration to support Greek language

server/api/models/User.js

@@ -63,6 +63,7 @@ const LANGUAGES = [
   'uz-UZ',
   'zh-CN',
   'zh-TW',
+  'el-GR',
 ];
 
 const PRIVATE_FIELD_NAMES = ['email', 'isSsoUser'];