A 42-year-old woman from Mumbai with a 12-year history of hepatitis B (HBsAg positive, anti-HBe positive) on no antiviral therapy presents with acute-onset jaundice, fever (38.5°C), right upper quadrant pain, and malaise for 5 days. She denies recent drug use or transfusion. Laboratory findings: total bilirubin 9.8 mg/dL, ALT 3200 IU/L, AST 2800 IU/L, ALP 220 IU/L, albumin 3.2 g/dL, INR 1.4. HBsAg remains positive; anti-HBc IgM is negative; HBV DNA is 8.5 × 10^6 copies/mL (previously 1.2 × 10^4 copies/mL 6 months ago). What is the most likely diagnosis?