LONDON — A London judge on Friday rejected a U.S. mother’s challenge to be extradited to Colorado to face murder charges in the deaths of two of her young children. Judge John Zani said in Westminster Magistrates Court that it would now be up to the British Home Secretary to order Kimberlee Singler returned to the United States. Singler, 36, is accused of two counts of first-degree murder in the December 2023 shooting and stabbings of her 9-year-old daughter and 7-year-old son, and one count of attempted murder in the knife slashing of her 11-year-old daughter. She also faces three