ObsEvent constructor

Creates a new ObsEvent.

This is a const constructor so that subclasses can also define constant event instances if needed.

A base class representing an event in an observable system.

Classes that extend ObsEvent define specific types of events that can be emitted, observed, or dispatched in reactive or event-driven architectures.

This is an abstract class and cannot be instantiated directly. Subclasses should provide additional context or payload relevant to the event.

Example:

class UserLoggedInEvent extends ObservableEvent {
  final String userId;

  const UserLoggedInEvent(this.userId);
}

// Usage
final event = UserLoggedInEvent("12345");