Arena, which develops the popular AI model leaderboard, raised 200M at a 3.1B valuation, up from $1.7B in January, and launches an Alignment Index (Rachel Metz/Bloomberg)Rachel Metz / Bloomberg: Arena, which develops the popular AI model leaderboard, raised 200M at a 3.1B valuation, up from 1.7B in January, and launches an Alignment Index — Arena Intelligence Inc., th