For weeks, it had been assumed, leaked and reported that President Obama’s library would come to this city’s South Side. On Tuesday, it finally became official. In an announcement posted early in the morning, the Barack Obama Foundation said the presidential library would be built in a park here, and not in New York or Hawaii, which were also considered. But the cheery message did not say which of two sprawling Chicago parks would be home to the library, nor did it mention a possible legal challenge to the project. “All the strands of my life came together, and I...