fix: unused param warning + @onready type mismatch for MovementStateMachine

- state_wall_run.gd: typed ray_origin/ray_end as Vector3
- test_level_builder.gd: restructure builder to put MovementStateMachine
  + state children under Player, attach camera under Player too
- player_movement_controller.gd: @onready uses get_node so type is not inferred

movement/movement_state_machine.gd

@@ -83,7 +83,7 @@ func switch_to(new_state_name: String, data: Dictionary = {}) -> void:
 	state_changed.emit(prev, new_state_name)
 
 
-func register_chain_mechanic(mechanic_name: String) -> void:
+func register_chain_mechanic(_mechanic_name: String) -> void:
 	if chain_timer > 0.0 and chain_count > 0:
 		chain_count = min(chain_count + 1, 10)
 	else: