Unity U3: Add DeckGenResponse.cs + GeneratedDeckCard (#48)

This file defines the DeckGenResponse class and its associated GeneratedDeckCard class, which map to the response structure from the /api/deckgen/v3 endpoint.

unity-client/Assets/Scripts/Models/DeckGenResponse.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Generic;
+using Newtonsoft.Json;
+
+namespace CommanderAILab.Models
+{
+    /// <summary>Maps to GeneratedDeckCard from /api/deckgen/v3.</summary>
+    [Serializable]
+    public class GeneratedDeckCard
+    {
+        [JsonProperty("scryfall_id")] public string scryfallId;
+        [JsonProperty("name")] public string name;
+        [JsonProperty("type_line")] public string typeLine;
+        [JsonProperty("mana_cost")] public string manaCost;
+        [JsonProperty("cmc")] public float cmc;
+        [JsonProperty("card_type")] public string cardType;
+        [JsonProperty("roles")] public List<string> roles;
+        [JsonProperty("source")] public string source;
+        [JsonProperty("quantity")] public int quantity;
+        [JsonProperty("image_url")] public string imageUrl;
+        [JsonProperty("owned_qty")] public int ownedQty;
+        [JsonProperty("is_proxy")] public bool isProxy;
+
+        public override string ToString() => $"{name} ({manaCost})";
+    }
+
+    /// <summary>Response wrapper for /api/deckgen/v3.</summary>
+    [Serializable]
+    public class DeckGenResponse
+    {
+        [JsonProperty("cards")] public List<GeneratedDeckCard> cards;
+        [JsonProperty("commander")] public string commander;
+        [JsonProperty("strategy")] public string strategy;
+
+        public override string ToString() => $"Generated deck: {commander} ({cards?.Count ?? 0} cards)";
+    }
+}