ECS refactor: new ComponentSet, serialization, generators

Major ECS API overhaul: added ComponentSet, refactored ComponentRegistry, and updated all entity/component creation methods. Introduced robust custom serialization infrastructure and per-component source generators for registration and (de)serialization. Updated editor, engine, and test code to use new APIs. Improved code quality, naming, and performance throughout. Removed obsolete code and updated dependencies.

Ghost.Entities/System.cs

@@ -61,12 +61,12 @@ public abstract class SystemBase : ISystem
         _requiredQueries.Add(queryID.value);
     }
 
-    public void Initialize(ref readonly SystemAPI systemAPI)
+    void ISystem.Initialize(ref readonly SystemAPI systemAPI)
     {
         OnInitialize(in systemAPI);
     }
 
-    public void Update(ref readonly SystemAPI systemAPI)
+    void ISystem.Update(ref readonly SystemAPI systemAPI)
     {
         if (ShouldUpdate())
         {
@@ -87,7 +87,7 @@ public abstract class SystemBase : ISystem
         }
     }
 
-    public void Cleanup(ref readonly SystemAPI systemAPI)
+    void ISystem.Cleanup(ref readonly SystemAPI systemAPI)
     {
         OnCleanup(in systemAPI);
     }
@@ -352,6 +352,8 @@ public class SystemManager
 
     private readonly List<ISystem> _systems = [];
 
+    internal IReadOnlyList<ISystem> Systems => _systems;
+
     internal SystemManager(World world)
     {
         _world = world;