Elon Musk's surprise Anthropic deal allows him to accomplish two things at once: turn unused compute into revenue before an expected SpaceX IPO next month — and stick it to his archrival, Sam Altman.Why it matters: Musk went from calling Anthropic "evil" to doing business with it in three months, showing how quickly competition can give way to strategic necessity in the AI race.The big picture: The deal helps Anthropic address one of its most pressing problems — a severe compute deficit. The com...