fix: force skeleton skin update at runtime for GLTF models

The AnimationPlayer correctly updates bone poses (proven in tests)
but the MeshInstance visual doesn't reflect the changes. Added
throttled _update_skin() that re-applies bone poses every ~33ms
to trigger NOTIFICATION_UPDATE_SKELETON on the Skeleton3D,
which causes the MeshInstance to update its vertex buffers.

Also set AnimationPlayer process_mode to ALWAYS to ensure it
processes regardless of parent node state.

characters/skinned_player_model.gd

@@ -101,7 +101,7 @@ func load_model(path: String) -> void:
 	animation_player = _find_animation_player(scene)
 	if animation_player:
 		# Ensure AnimationPlayer processes even if parent has process_mode disabled
-		animation_player.process_mode = Node.PROCESS_MODE_INHERIT
+		animation_player.process_mode = Node.PROCESS_MODE_ALWAYS
 		animation_player.active = true
 		print("SkinnedPlayerModel: AP process_mode=%d active=%s" % [animation_player.process_mode, animation_player.active])
 		var anim_list = animation_player.get_animation_list()
@@ -303,13 +303,16 @@ func _add_animation_to_player(ap: AnimationPlayer, anim_name: String, anim: Anim
 	print("SkinnedPlayerModel: added '%s' (%d tracks)" % [anim_name, anim.get_track_count()])
 
 func _update_skin() -> void:
-	## Force skeleton skin update by notifying the Skeleton3D that bones changed.
+	## Force skeleton skin update by re-applying current bone poses.
 	## GLTF runtime loaded models sometimes need this because the AnimationPlayer's
 	## internal bone pose updates don't always trigger the visual pipeline.
 	# Re-apply current bone poses to ensure dirty flags are set.
 	# This triggers NOTIFICATION_UPDATE_SKELETON on the Skeleton3D.
 	for i in range(skeleton.get_bone_count()):
 		skeleton.set_bone_pose(i, skeleton.get_bone_pose(i))
+	# Also notify the MeshInstance that its skeleton changed
+	if _mesh_instance:
+		_mesh_instance.skeleton = _mesh_instance.skeleton
 
 func _setup_first_person() -> void:
 	# In first person, hide the head and upper body so only arms/hands/legs show