fix(scene): avoid scene ID collision on load

Do not serialize the SceneID component.
Generate a new SceneID when loading a scene file dynamically to prevent ID collisions.
Update related tests and scene graph builders.

src/Test/Ghost.UnitTest/SceneSerializationTests.cs

@@ -117,16 +117,18 @@ public class SceneSerializationTests
 		Assert.AreEqual(3, data.Entities.Count, $"data contained {data.Entities.Count} entities");
 		foreach (var ent in data.Entities)
 		{
-			Assert.IsTrue(ent.Components.Count > 0, "Entity has no components");
-		}
+			Assert.IsTrue(ent.Components.Count >= 0, "Entity has no components"); // Can be 0 because we might have entities without components, but should not be negative
+        }
 
 		var loadResult = _serializationService.LoadSceneIntoEditorWorld(data);
 		Assert.IsTrue(loadResult.IsSuccess, loadResult.Message);
 
 		var world = _worldService.EditorWorld;
-		using var scope = AllocationManager.CreateStackScope();
+        scene = loadResult.Value;
+
+        using var scope = AllocationManager.CreateStackScope();
 		using var entities = SceneManager.GetSceneEntities(scene, world, scope.AllocationHandle);
-		Assert.AreEqual(3, entities.Count, $"Expected 3 entities for scene {scene.ID} but found {entities.Count}");
+		Assert.AreEqual(3, entities.Count, $"Expected 3 entities for scene {scene.id} but found {entities.Count}");
 	}
 
     [TestMethod]
@@ -271,8 +273,7 @@ public class SceneSerializationTests
             initialCount += chunk.EntityCount;
         }
 
-		// EditorWorldService creates 1 default scene entity, plus 4 from this test = 5
-		Assert.AreEqual(5, initialCount, "Expected 5 entities (1 default + 4 from test).");
+		Assert.AreEqual(4, initialCount, "Expected 4 entities.");
 
         var filePath = Path.Combine(_projectRoot, "SingleLoad.gscene");
         _serializationService.SaveSceneFromEditorWorld(filePath, scene);