At 1 p.m. on a warm spring Thursday, a crowd spills onto the sidewalk at Melrose and Western in Los Angeles — long one of the city’s more commercially undesirable intersections, but today an epicenter of cool. Influencers and the casually affluent, purse dogs in tow, they’re here for jamón serrano y queso arepas, coconut cream pie, and strawberry cheesecake matcha lattes at Chainsaw, the Venezuelan pop-up-turned-bakery and cafe from Karla Subero Pittol that has quickly become one of the most