Foundations: OnuProvider, RTL, Dhivehi locale & i18n #5

REQUIREMENTS §11, §12, §15 (R15.8), §16.

• OnuProvider (locale, direction, link component, icons, defaults, density, map config)
• DirectionProvider wrapping Radix's; components respect nearest dir
• Locale dictionaries en + dv for every built-in string, with interpolation and pluralisation; consumer overrides
• Dhivehi date-fns locale (months, weekdays, relative time); week start config
• Intl.Collator-based sorting/search helpers
• cn(), visually hidden and live-region utilities
• Laravel helpers: 422 error mapping (dot-notation → fields, setError), paginator meta/links parsing