Update macro goals for a user (admin override)

{
  "userId": 5,
  "calories": 1500,
  "protein": 100,
  "carbs": 150,
  "fat": 50,
  "fiber": 25,
  "reason": "Post-surgery stage 3 adjustment"
}

{
  "success": true,
  "message": "Macro goals updated"
}