Susan Graham is one of those rare singers who combine broad audience appeal with critical approbation. She has won a Grammy, for a stellar CD of Charles Ives songs with Pierre-Laurent Aimard, and sings on the greatest operatic stages of the world, in works ranging from Mozart to new operas like Tobias Picker’s An American Tragedy. It was hardly surprising, therefore, that Graham’s recital on Friday night in the Kennedy Center Terrace Theater was sold…