A 2-year-old girl is admitted to a district hospital with severe wasting, loss of subcutaneous fat, visible ribs and spine, and no pitting oedema. Weight is 8 kg (expected 12 kg for age). Serum albumin is 2.8 g/dL, and total serum protein is 5.2 g/dL. Mother reports the child has been on diluted cow's milk and rice porridge for the past year due to financial constraints. After stabilization and treatment of infections, what is the most appropriate next step in nutritional management?