The first significant indie hit of 2024, Alex Garland’s “Civil War,” was a disturbing film to drop during an election year. Writer-director Garland (“Ex Machina,” “Annihilation”) created a hellscape with echoes of conflicts in places like Ukraine, but also one that nodded to the ugly divisions of January 6 and escalated them into a harrowing portrait of an angry America at war with itself. “When we started rehearsal, the war in Ukraine broke out,” said Kirsten Dunst, who stars in the film as