Add fluent configuration pipeline API

[stevebauman]

Adds a Laravel-style fluent API for parser/refiner configuration without changing the public Chrono with/without methods.

Changes:

• Adds Configuration::make(), parsers(), refiners(), hasParser(), hasRefiner()
• Adds add/prepend/remove methods for parsers and refiners
• Updates ConfiguredChronoEngine to delegate configuration mutations through Configuration
• Adds focused system coverage for the fluent pipeline API

Verification:

• ./vendor/bin/pest tests/system.test.php --do-not-cache-result
• ./vendor/bin/pint --test