Koiusa Actor MMD Adapter

Connects LibMmd model instances to com.koiusa.actor.runtime without changing LibMmd's native animation, rendering, or physics update paths.

MmdActor exposes scene-object and playback features directly. Applications can supply their own motion, appearance, and physics features so catalogs, localization, persistence, and model-replacement policy remain outside the format runtime.

Use MmdActorProvider with an IMmdActorLoader, register it in an ActorProviderRegistry, and replace actors through ActorSession. Configure MmdActorProviderOptions to resolve stable actor IDs and construct optional features. The loader owns each uncommitted model instance, including cancellation and disposal; a failed load therefore leaves the current session actor unchanged.