A 38-year-old male presented with fatigue, sore throat, and low-grade fever for 3 days. He was treated for upper respiratory tract infection (URI) with amoxicillin and herbal medicine for 5 days. The sore throat and fever resolved, but fatigue worsened, accompanied by blurred vision in the left eye, petechiae, and ecchymoses on the trunk and lower limbs. Lab results: WBC 2.5×10<sup>9</sup>/L, Hb 90g/L, PLT 32×10<sup>9</sup>/L. Physical exam: no lymphadenopathy or hepatosplenomegaly, marked sternal tenderness. Bone marrow aspiration showed 89% blast cells with coarse cytoplasmic granules, frequent Auer rods, and strongly positive POX staining. Persistent bleeding at the puncture site. The most likely diagnosis is: