Variable dropIdentityTransformConst

dropIdentityTransform: Fix = ...

Auto-fix for TRANSFORM_IDENTITY — re-parents every referencer (meshes + child transforms) of an identity SceneTransform to its grandparent (or detaches them if the identity is at the root), then destroys it. World poses are preserved without preserveWorld: true because the missing factor is the 4×4 identity — multiplying by it has no effect.

SceneTransform.destroy would otherwise leave dangling mesh.parentTransform references, since transforms (unlike materials / textures) carry no destroy-time guard against mesh referencers. This fix closes that gap explicitly.

Idempotent: returns {fixed: false} when the transform is already destroyed or absent.