PARIS — Novak Djokovic won his first Olympic gold medal by beating Carlos Alcaraz 7-6 (3), 7-6 (2) in an enthralling men’s tennis singles final Sunday, giving the 37-year-old from Serbia the last significant accomplishment missing from his glittering resume. Djokovic’s impressive career already featured a men’s-record 24 Grand Slam titles and the most weeks