JERUSALEM — Nearly 30 young people took refuge inside a grimy bunker on the morning of Oct. 7, hoping the reinforced-concrete shelter near the border with Gaza would fulfill its promise of protection. But just after 7:40 a.m., when a group of Hamas assailants, armed with assault rifles and grenades, attacked the shelter near Kibbutz Re’im in southern Israel, the very characteristics that made the tiny fortress a refuge from incoming rockets turned it into a deathtrap for those inside. In less th