minor fix

src/aeros_simulation/service.py

@@ -46,7 +46,7 @@ async def get_simulation_by_id(
     if simulation_id:
         query = query.where(AerosSimulation.id == simulation_id)
     else:
-        query = query.order_by(AerosSimulation.created_at.desc()).limit(1)
+        query = query.order_by(AerosSimulation.completed_at.desc()).limit(1)
 
     results = await db_session.execute(query)
     return results.scalar()