A 32-year-old man from rural Maharashtra presents with jaundice, dark urine, and pale stools for 10 days. He reports consuming contaminated water from a well 4 weeks ago. On examination, he is afebrile with hepatomegaly and mild splenomegaly. Laboratory investigations show: Total bilirubin 8.2 mg/dL, ALT 1840 IU/L, AST 1620 IU/L, ALP 320 IU/L, albumin 3.8 g/dL, PT-INR 1.1. Serology: Anti-HAV IgM positive, Anti-HBc negative, Anti-HCV negative. What is the most likely diagnosis?