In Yukon, Oklahoma, Czech immigrants planted roots more than a century ago—and their descendants are still baking, dancing, and debating kolache fillings.Credit: Jacob Fox / Food Stylist: Shannon GoForth / Prop Stylist: Kristen SchooleyOn Saturday nights at Yukon’s Czech Hall, just south of historic Route 66 in Oklahoma, Kim Rex is already behind the bar, greeting neighbors as the polka band arrives and her fellow volunteers finish setting up fo…