SEOUL, South Korea — South Korea’s foreign minister departed for the U.S. on Monday to finalize steps for the return of several hundred South Korean workers detained last week in a massive immigration raid in Georgia, as the incident caused confusion, shock and a sense of betrayal among many in the U.S.-allied nation. The Sept. 4 raid on a battery factory under construction at a sprawling Hyundai auto plant in Georgia led to the detainment of 475 workers, more than 300 them South Koreans. Some