Raising venture capital money has been a breeze for Decagon AI Inc., a two-year-old startup developing artificial intelligence tools for customer service.All four of Decagon’s funding rounds, totaling more than $230 million, were preempted, meaning firms like Andreessen Horowitz offered to invest before the company started fundraising. Now, just three months after a round that valued it at $1.5 billion, Decagon is fielding unsolicited offers at valuations as high as $5 billion, according to peop...