A 35-year-old Indian man with a 10-year history of chronic hemolytic anemia presents with jaundice, splenomegaly, and pigmented gallstones on ultrasound. He reports recurrent episodes of severe abdominal pain and dark urine, particularly during febrile illnesses. His hemoglobin is 8.5 g/dL, reticulocyte count 15%, and indirect bilirubin is elevated. The osmotic fragility test shows increased fragility of RBCs. Direct antiglobulin test is negative. Peripheral blood smear reveals spherocytes and polychromasia. What is the most likely diagnosis?