Document route() throw behavior and hasRoute predicate

[rubenvanassche]

Summary

Adds a "Handling unknown routes" section to the Laravel routes docs covering:

• The generated route() helper now throws on unknown route names (matching Laravel's server-side RouteNotFoundException behavior).
• The new hasRoute(name): name is keyof RouteParameters type predicate exported alongside route(), mirroring Laravel's Route::has().
• Example usage for dynamic-name callers (locale-aware routing, runtime-composed keys) showing how the predicate narrows the type.

Documents the behavior introduced in spatie/laravel-typescript-transformer#85.