DTOs for index mostly done, doing DB models

DCGEngine.Database/Models/CardSetEntry.cs

@@ -0,0 +1,17 @@
+namespace DCGEngine.Database.Models;
+
+/// <summary>
+/// A set containing 0 or more <see cref="CardEntry"/>s. All cards must belong to a set.
+/// </summary>
+public abstract class CardSetEntry : BaseEntity<int>
+{
+    /// <summary>
+    /// The internal name of the set.
+    /// </summary>
+    public virtual string Name { get; set; } = string.Empty;
+    
+    /// <summary>
+    /// The cards in the set.
+    /// </summary>
+    public virtual List<CardEntry> Cards { get; set; } = new List<CardEntry>();
+}