A 2-year-old girl from Delhi is brought to the pediatric emergency department with acute-onset watery diarrhea and vomiting for 18 hours. Her parents report she has had 6–7 stools in the last 6 hours and is refusing feeds. On examination, she is alert and playful, eyes are slightly sunken, she drinks eagerly when offered water (though vomits shortly after), and skin turgor is mildly decreased (pinch goes back in <2 seconds). Capillary refill is normal. Her weight is 13 kg (baseline 13.5 kg). Serum sodium is 135 mEq/L, potassium 3.8 mEq/L, and HCO₃⁻ is 18 mEq/L. What is the most appropriate fluid management plan?