Astrid Lancieaux has come from France to stay with us for a few weeks. Charlie wants her to be his new best friend. Sunday he took her to the Capitol, the Botanic Gardens, and the pool, and last night he took her to a performance of young chamber musicians (Astrid plays the cello) at the Kennedy Center and to her first Mexican restaurant visit. Today he took her to the Phillips Collection, but wasn’t as successful a guide there, what with his screaming.