♻️ refactor: harden architecture and extensibility

[proxynth]

Description

Ce changement finalise le refactoring de LaraWebhook selon une architecture hexagonale ciblée, avec séparation claire entre application, domaine et infrastructure Laravel.

Principaux changements :

• séparation validation, audit, replay et retry en use cases applicatifs ;
• introduction de ports et adapters pour les dépendances externes ;
• extraction des responsabilités Laravel dans Infrastructure ;
• amélioration des read models et de la persistance des logs ;
• support des services webhook configurables hors enum ;
• parseurs et validateurs personnalisables ;
• sécurisation de la CI, de Composer et de PHPStan ;
• documentation de la façade et des méthodes legacy.

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to change)
• 📝 Documentation update
• 🔧 Configuration change
• ♻️ Refactoring (no functional changes)
• ✅ Test update

Checklist

• I have read the CONTRIBUTING guidelines
• My code follows the project coding standards
• I have run composer format
• I have run composer analyse and fixed any issues
• I have added tests that prove my fix/feature works
• All new and existing tests pass (composer test)
• I have updated the documentation where applicable
• I have updated the CHANGELOG.md (not applicable; Release Please manages releases)

Screenshots / Output

• Pint : passed
• PHPStan : 143/143, no errors
• Tests : 629 passed, 1 skipped, 1588 assertions

Additional Notes

The branch contains one cohesive refactoring commit and is ready for review.