Function isLocaleSupported

Internationalization support. Provides localized month names, day names, zodiac names, solar term names, and GanZhi characters for each locale.

isLocaleSupported(code: string): code is LocaleCode
Check if a locale code is supported
Parameters
- code: string
  Locale code to check
Returns code is LocaleCode
true if the locale is supported (type-narrows to LocaleCode)
Example
```
isLocaleSupported('zh-CN')   // true
isLocaleSupported('en-US')   // false
```
- Defined in locale.ts:259