A 2-year-old girl from urban Delhi presents with acute watery diarrhea (12 stools in 24 hours) and vomiting for 2 days. On examination: alert, normal skin turgor, normal mucous membranes, capillary refill <2 seconds, urine output maintained. Weight 12 kg. Stool culture is pending. The child has received 3 doses of rotavirus vaccine. What is the most appropriate next step in management?