curl --request GET \
  --url http://localhost:3000/v1/inventory/summary

{
  "total_items": 123,
  "total_units": 123,
  "inventory_on_hand_cost": 123,
  "avg_days_on_hand": 123,
  "avg_inventory_age_days": 123,
  "avg_daily_demand": 123
}