Add support for locale: '*' to use all available locales

[Copilot]

This PR adds support for using locale: '*' in both translate and localize methods to automatically use all available locales, building on the existing multiple locales functionality.

Changes

• Enhanced translate method: Now accepts locale: '*' to translate keys across all available locales
• Enhanced localize method: Now accepts locale: '*' to localize objects across all available locales
• Backward compatible: All existing functionality remains unchanged

Usage Examples

# Before: You had to explicitly specify all locales
MiniI18n.t(:hello, locale: [:en, :es, :fr])
#=> ["hello", "hola", "bonjour"]

# Now: Use '*' to automatically include all available locales
MiniI18n.t(:hello, locale: '*')
#=> ["hello", "hola", "bonjour"]

# Works with interpolation
MiniI18n.t(:greeting, name: 'world', locale: '*')
#=> ["hello world", "hola world", "bonjour world"]

# Also works with localization
MiniI18n.l(1234.56, locale: '*')
#=> ["1,234.56", "1.234,56", "1 234,56"]

MiniI18n.l(1000, as: :currency, locale: '*')
#=> ["1,000 $", "1.000 €", nil]

Implementation Details

The implementation is minimal and leverages the existing multiple locales infrastructure:

1. Added helper methods that convert locale: '*' to locale: available_locales array
2. This conversion happens before the existing array handling logic
3. The feature automatically adapts when available_locales changes

Testing

Added comprehensive tests covering:

• Translation with '*' locale
• Translation with interpolation and '*' locale
• Localization with '*' locale
• Currency formatting across all locales
• Edge cases and backward compatibility

All existing tests continue to pass, ensuring no regression in functionality.

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