ScriptComponent stores only a script name string (POD, serializable);
instances are reconciled by ScriptRuntime each frame (PhysicsWorld
pattern): orphan/rename cleanup with OnDestroy, per-name instantiation
from a file-level self-registering registry (ENGINE_REGISTER_SCRIPT),
OnCreate on bind, OnUpdate after physics step on scaled dt. Engine
framerate loop only sees the base interface, so future Lua/C# behaviors
plug in as foreign ScriptBehavior implementations with zero engine
changes. Ships a Spinner sample script and Inspector script picker.
