Katharine McPhee, who stars on NBC’s “Smash,” was seen celebrating her 29th birthday at the General with friends and family this week. Among gifts scattered on the table were a dramatic pair of black studded Christian Louboutin heels. “She let out a squeal when she saw them,” says a spy. “And then said, ‘These are the ones I’ve been wanting!’ ” The night ended with the group, including her husband Nick Cokas, singing “Happy Birthday” around a custom, multitier cake.