Still looking for the perfect Christmas gift for the music lover in your life? The music critics of the New York Times are here to help, with their annual roundup of the best classical CDs of 2006. On the list this year: Lorraine Hunt Lieberson’s last album, the London Symphony’s Beethoven cycle, plenty of Mozart (have you heard? It’s his 250th birthday!), and a new Concertgebouw recording of Stravinsky.