Expose entity lifecycle events on World

[AristurtleDev]

Description

This pull request exposes entity lifecycle events on the World class, allowing external systems to react when entities are added, removed, or have their component composition changed. This enables integration between the ECS and other subsystems (such as CollisionComponent) without requiring each system to implement its own entity tracking.

The events are raised during the World.Update() cycle and provide entity IDs to subscribers, who can then perform necessary initialization or cleanup operations.

Related Issues/Tickets

• Closes [Feature Request]: Expose events to entities being added and removed from an ECS world #1026

Changes Made

• Added three public events to World class:
  • EntityAdded : Fires when an entity is added to the world during the update cycle
  • EntityRemoved: Fires when an entity is removed from the world during the update cycle (before destruction)
  • EntityChanged: Fires when an entity's component composition changes
• Event wiring in World constructor: Subscribes to internal EntityManager events to forward them to public subscribers
• Cleanup in World.Dispose(): Unsubscribes from EntityManager events

Bug Fixed

• Fixed duplicate EntityChanged invocation in EntityManager: Removed immediate event invocation in OnComponentsChanged() to ensure the event only fires once during the Update() cycle, consistent with EntityAdded and EntityRemoved behavior

Checklist

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• I have provided appropriate test coverage were applicable.