- Add locale field to AppSettings model with 'system' default
- Add Language section in Appearance settings page
- Support System Default, English, and Indonesian options
- App language changes take effect immediately
- Add localization strings for language selector
- Add description field to all 400+ localization strings
- Mark brand names and technical terms as DO NOT TRANSLATE
- Add placeholder descriptions for parameterized strings
- Helps translators understand context for each string