Explain PHP 8.3's new features including typed class constants, dynamic class constant fetch, and readonly amendments. Provide practical examples.

PHP 8.3 introduces several significant features:

1. Typed Class Constants:
You can now specify types for class constants, improving type safety:

class MyClass {
    public const string NAME = "MyClass";
    public const int VERSION = 1;
    public const array CONFIG = ["debug" => true];
}

2. Dynamic Class Constant Fetch:
Allows fetching class constants dynamically using variables:

class Status {
    const ACTIVE = "active";
    const INACTIVE = "inactive";
}

$constantName = "ACTIVE";
$value = Status::{$constantName}; // Returns "active"

3. Readonly Amendments:
- Readonly properties can now be reinitialized during cloning - Better support for readonly properties in inheritance - Improved readonly class behavior

Benefits: Enhanced type safety, better performance, improved developer experience, and more robust object-oriented programming capabilities.