Exercise baseline

src/Domain/Order.cs

@@ -0,0 +1,17 @@
+namespace Domain;
+
+/// <summary>A plain domain order: no persistence base class, no persistence context knowledge.</summary>
+public class Order
+{
+    /// <summary>Identity: <see cref="Guid.Empty"/> until the persistence layer assigns one on save.</summary>
+    public Guid Id { get; set; }
+
+    /// <summary>Free-text description of what this order is for.</summary>
+    public string Description { get; set; } = string.Empty;
+
+    /// <summary>Order total in cents (non-negative by convention); the DTO and storage row carry the same plain int.</summary>
+    public int TotalInCents { get; set; }
+
+    /// <summary>The owning client; wired by navigation fix-up when the order is added to <see cref="Client.Orders"/>.</summary>
+    public Client? Client { get; set; }
+}