Ashley St. Clair, a 27-year-old former brand ambassador for Charlie Kirk's Turning Point USA, has turned into one of the fiercest critics of the movement she helped build.St. Clair, who amassed more than a million followers on X, published an anti-transgender children's book, appeared on Fox News and took selfies at Mar-a-Lago, now alleges that many of President Donald Trump's top online cheerleaders are "mercenaries of the attention economy" co…