A 32-year-old woman from rural Odisha presents with fever, chills, and sweating for 3 days. She reports that fever spikes occur every 48 hours with a pattern of cold stage (15 min), hot stage (2 hours), and sweating stage (1 hour). On examination, she is febrile (39.5°C), with mild hepatosplenomegaly. Thick blood smear shows ring forms and Schüffner's stippling. Rapid diagnostic test (RDT) is positive for P. vivax. Which of the following is the most appropriate initial management according to NVBDCP guidelines?