A 38-year-old man from Delhi presents with a 3-month history of progressive fatigue, dyspnea, and recurrent infections. On examination, he is pale and has mild splenomegaly. Laboratory findings: hemoglobin 7.8 g/dL, MCV 68 fL, reticulocyte count 0.8% (normal: 0.5–2.5%), serum iron 32 μg/dL (normal: 60–170), serum ferritin 680 ng/mL (normal: 30–300), and transferrin saturation 18% (normal: 20–50%). Peripheral blood smear shows microcytic hypochromic red cells with target cells. What is the most likely diagnosis?