Add Entity.ID and EntityRef.ID

src/gaemstone/ECS/Entity.cs

@@ -39,6 +39,7 @@ public readonly struct Entity
 	public static readonly Entity None = default;
 
 	public readonly ecs_entity_t Value;
+	public uint ID => (uint)Value.Data;
 
 	public bool IsSome => Value.Data != 0;
 	public bool IsNone => Value.Data == 0;

src/gaemstone/ECS/EntityRef.cs

@@ -12,6 +12,7 @@ public unsafe sealed class EntityRef
 {
 	public override Universe Universe { get; }
 	public Entity Entity { get; }
+	public uint ID => Entity.ID;
 
 	public bool IsValid => ecs_is_valid(Universe, this);
 	public bool IsAlive => ecs_is_alive(Universe, this);