[MEDIUM] ScriptableObject default diff leaks temporary instance on serialization failure

[Daliys]

Problem

diff_scriptable_object_against_defaults creates a temporary ScriptableObject instance and only destroys it after the diff loop completes successfully.

Evidence

• Editor/MCPServerMethods.ScriptableObject.cs:30 creates defaults = ScriptableObject.CreateInstance(so.GetType()).
• Editor/MCPServerMethods.ScriptableObject.cs:36-54 serializes and compares properties.
• Editor/MCPServerMethods.ScriptableObject.cs:56 destroys defaults, but this is not inside a finally.

Impact

If property serialization/comparison throws, the temporary ScriptableObject remains alive until domain reload. Repeated failing calls can accumulate hidden objects.

Suggested fix

Wrap the diff loop in try/finally and call DestroyImmediate(defaults) in the finally when the instance was created.

Source report

Imported from audit report item: resource-leak (9) / Editor/MCPServerMethods.ScriptableObject.cs:56.