NEW YORK—Iga Swiatek beat Ons Jabeur 6–2, 7–6 (5) in the U.S. Open final on Saturday to claim her first championship at Flushing Meadows and third Grand Slam title overall. The No. 1-ranked Swiatek cemented her status as the dominant figure in women’s tennis by triumphing at the tournament that is expected to be the…