TALA MADANI’S paintings, drawings, and stop-motion animations of violent men, sadistic babies, and filth-covered moms plumb our most savage depths. To mark the artist’s first institutional survey, now on view at the Museum of Contemporary Art in Los Angeles, critic Sarah Lehrer-Graiwer weighs in on the surprising “cheerful air” and “basic beauty” that underpin the LA-based artist’s deliriously perverted tableaux.IT STARTS PLAYFULLY with a cake in the face. Ha ha. Just a joke. Right? Birthday candles burn in eye sockets, confections rise vertically like giant phalluses or balance on the backs of