Introduce `toJSON` and `fromJSON` methods to the `World` class to
allow saving and restoring world states. This requires components and
relationships to have human-readable names for stable serialization.
Introduces relationship management to the World, including
storage for forward and reverse relationships. Adds new observable
events and a `RelationshipUpdate` stream to track when relationships
are added or removed.
Initial implementation of an Entity-Component-System (ECS) featuring:
- Sparse set-based component storage for efficient access.
- Entity lifecycle management with generation-based recycling.
- Reactive query system using RxJS for change tracking.
- Batched event flushing to support frame-based updates.
- Type-safe component definitions via TypeScript inference.
hypercross