Nvidia just paid $12.9 billion for a company famous for giving away AI models for free. Last year, Hugging Face turned down a $500 million Nvidia investment at a $7 billion valuation. Today Nvidia bought the whole thing for nearly double. The price looks insane until you see who Nvidia is defending against. Its biggest customers are all building escape routes. OpenAI is designing chips with Broadcom. Anthropic trains on Amazon's Trainium. Google has run its own TPUs for a decade. The labs…