use native-time-ago

[chinesepowered]

Summary

This PR replaces the bundled language strings with native-time-ago, a zero-dependency library that uses the native Intl.RelativeTimeFormat API.

Benefits:

• ✅ Zero dependencies (removes 70+ bundled locale files)
• ✅ Supports 100+ languages automatically via browser's native API
• ✅ Translations improve as browsers update (no locale maintenance)
• ✅ Smaller bundle size

Changes:

• Added native-time-ago@1.0.1 dependency
• Updated component to use Intl.RelativeTimeFormat with numeric: 'auto' for natural strings like "yesterday" instead of "1 day ago"
• Added locale prop (defaults to 'en')
• Auto-updates every 60 seconds when live={true}
  Migration: The API is nearly identical. Usage like <TimeAgo date={date} locale="es" /> works the same way.