Integrate Spatie Laravel Permission to replace the legacy role system.
This includes:
- Adding `spatie/laravel-permission` dependency.
- Implementing `Role` and `User` model updates with `HasRoles` trait.
- Adding migrations for permission and role tables.
- Creating `RoleResource` and `UserResource` for Filament administration.
- Adding a `RoleAndPermissionSeeder` for initial setup.
- Updating `User` model helper methods to utilize role checks.
