A 28-year-old man from Delhi presents with jaundice, dark urine, and abdominal discomfort for 10 days. He reports eating raw shellfish at a street vendor 4 weeks ago. On examination, he is afebrile, icteric, with hepatomegaly but no ascites. Laboratory findings: total bilirubin 8.2 mg/dL (direct 6.1 mg/dL), ALT 2840 IU/L, AST 2100 IU/L, ALP 180 IU/L, albumin 3.8 g/dL, INR 1.1. Anti-HAV IgM is positive; anti-HBc, anti-HCV are negative. Abdominal ultrasound shows no cirrhotic features. What is the most likely diagnosis?