WASHINGTON — The U.S. Army wants to make its command posts nimbler and more easily concealable to survive intense, widespread fights of the future, and it’s pulling lessons from the invasion of Ukraine to inform the effort. Command posts of the past were relatively stationary, cumbersome to set up and break down, and often identifiable by the heat, noise and electronic artifacts they give off. Such easy targets will not cut it in a fight against China or Russia, world powers with mature sensing