NEW YORK — Jessica Pegula may be an admirable, 30-something workaholic, but Aryna Sabalenka is a screeching, hammering force of nature. That irresistible power, plus some acrobatic, nuanced shots, carried Sabalenka to a 7-5, 7-5 victory on Saturday, earning her a third major title and her first US Open championship. America’s chances in this tournament now reside with Taylor Fritz, who faces …