," notes  Judy Kaye .  " Everyone else is filled with doubt ."   Kaye, who starred as Mrs. Lovett in last year's production of Sweeney Todd: The Demon Barber of Fleet Street  at the  American Conservatory Theatre , is back onstage at the Geary Theater in A.C.T.'s new production of Stephen Temperley's  Souvenir: A Fantasia On The