feat: update translations via @lingodotdev (#1964)

Hey team,

[**Lingo.dev**](https://lingo.dev) here with fresh translations!

### In this update

- Added missing translations
- Performed brand voice, context and glossary checks
- Enhanced translations using Lingo.dev Localization Engine

### Next Steps

- [ ] Review the changes
- [ ] Merge when ready
    
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## Summary by cubic
Added complete Simplified and Traditional Chinese translations for the mail app, improving support for zh-CN and zh-TW users. All messages were checked for brand voice, context, and glossary consistency.

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Author: github-actions[bot]