Barcelona boosted their midfield by signing Franck Kessie as a free agent on Monday. The 25-year-old Kessie, who had been playing for AC Milan since 2017, arrives on a contract until June 2026 and a buyout clause of 500 million euros. Kessie moved to Italy in 2014 to sign for Atalanta, where he played in the club’s youth squads before …