The Miku model T-posed because the previous _update_skin() used
set_bone_pose(i, get_bone_pose(i)) which is a no-op when the pose
is unchanged. Replace with skeleton.notification(NOTIFICATION_UPDATE_SKELETON)
to force the Skeleton3D to recompute bone transforms and notify the
MeshInstance to update vertex buffers.
Also fix scale: the GLB is ~1.2m tall (not 1.6m as documented), so
set scale_factor=1.25 to fit the 1.8m player capsule, and add
position_y_offset=-0.2 to align the model's feet with the player origin.
Co-Authored-By: Hermes Agent <[email protected]>