The much-anticipated follow-up to Todd Phillips’ Golden Lion and Oscar-winning film is here and… Well, best not to turn your frowns upside down. Joker: Folie À Deux is less of a victory lap and more of a fumbled slog. We catch up with Arthur Fleck (Joaquin Phoenix) in Arkham Asylum. He’s awaiting trial for the murder of five people, and gets signed up for a music therapy class. Because that’s apparently the reward you get for taking your meds and behaving. There, he meets Harleen “Lee” Quinzel (Lady Gaga), an arsonist who is a big fan of Joker’s, isn’t afraid to lie when she needs to, and ha…