A 5-year-old girl from Kerala presents with mild pallor and jaundice. Her hemoglobin is 9.8 g/dL, MCV 68 fL, and reticulocyte count 4.2%. Peripheral smear shows hypochromic microcytic RBCs with occasional target cells and anisopoikilocytosis. Hemoglobin electrophoresis shows HbA 65%, HbA2 5.2%, and HbF 2%. The child is asymptomatic and has never required transfusion. What is the most likely diagnosis?