…IANA compliance

- Introduced `parseLocale` in `IanaSubtagRegistry` to parse locales into `ParsedTag`.
- Added `getParsedTag` in `BCP47Tag` for accessing parsed tag components.
- Marked `BCP47Parser` and `BCP47Normalizer` as `readonly` for immutability.
- Extended test suite with cases for `ParsedTag` functionality.

- Added `parseTagInternal` to centralize `ParsedTag` creation.
- Updated `parseLocale` and `isValidLocale` to reuse `parseTagInternal`, ensuring consistency.
- Improved type handling and null checks in `isValidLocale`.
- Updated README with examples and method documentation.

- Added `array<string>` type hints to `IanaSubtagRegistry` constructor for improved type safety.
- Removed redundant condition in `BCP47Parser::parseTag` for better clarity and reduced false positives.
- Updated documentation and passed all tests and PHPStan checks.

…timize lazy loading

- Replaced JSON IANA registry with static PHP snapshot for zero parsing overhead
- Removed symfony/intl and validator dependency (not needed after refactor)
- Implemented singleton lazy loader for registry (OPcache-friendly)
- Updated composer with bcp47:refresh script for manual IANA updates
- Cleaned up normalizer logic (pure ABNF-based, no external fallback)
- Updated README to reflect new structure and performance design
- All tests green, code lighter, faster, and fully self-contained

…IANA compliance

- cleanups
- test provider updates
- composer lock update

…d and README.md