Photo-Illustration: Vulture; Photos: Everett Collection (Walt Disney, Marvel, Miya Mizuno/Columbia Pictures), Jessica Miglio/Warner Bros. The first sign came in late April, hinting that Hollywood might be in for a summer of what entertainment-industry trade papers once upon a time called “boffo box office.” Over a weekend that’s normally a dead zone on the film calendar, a grab bag of titles unexpectedly packed in audiences: Ryan Coogler’s controversial blues vampire thriller Sinners (in its