Panida Wijitpanya | Istock | Getty Images Short sellers are increasingly hunting for cracks beneath the stock market's artificial-intelligence frenzy, betting that some of the speculative excesses, copycat "AI" branding and vulnerable legacy business models could eventually unravel. As billions of dollars flood into data centers, semiconductors and AI software, some short sellers argue the rally is beginning to resemble previous speculative manias, where weaker companies rushed to attach themselves to the hottest market theme in hopes of attracting capital and retail traders. "A rising tide lifts all boats, and a twisting tide takes down a lot of names in the same neighborhood," Joyce Meng, founder of Fact Capital, said during a panel discussion at Sohn Investment Conference this week in New York.…