A mural of President Jovenel Moïse near the home where he was killed by assassins in Haiti, July 13, 2021. Haitian election officials have set elections for Dec. 13, but many experts say extreme violence is likely to cause a postponement. Again. (Federico Ríos/The New York Times) By ANDRÉ PAULTRE and FRANCES ROBLES Gang violence in Haiti is so bad that Antoine Rodon Bien-Aimé, a candidate for the Haitian Senate, has been campaigning via speakerphone and video calls to community meetings….