Thalassemia trait vs. iron deficiency anemia in children

A 3-year-old boy is brought to the pediatric outpatient clinic with a 2-week history of progressive pallor, irritability, and poor feeding. On examination, he is pale, has mild hepatosplenomegaly, and no lymphadenopathy. Laboratory investigations reveal: hemoglobin 6.5 g/dL, MCV 58 fL, serum ferritin 450 ng/mL, and serum iron 180 µg/dL. Peripheral blood smear shows microcytic hypochromic RBCs with target cells. The child's mother reports he drinks 1.5 liters of cow's milk daily and eats very few iron-rich foods. What is the most likely diagnosis?