A 32-year-old woman from rural Odisha presents with fever, chills, and sweating for 3 days. She reports the fever occurs every alternate day, with temperatures reaching 40°C. On examination, she is pale with mild splenomegaly. A blood smear taken during the fever spike shows ring forms and Schüffner's stippling. She has no history of antimalarial prophylaxis. What is the most appropriate first-line antimalarial regimen for this patient according to NVBDCP guidelines?