Prebuilt deck purchasing and fixes

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/BuildDeck/BuildDeckBuyResponse.cs

@@ -0,0 +1,22 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses.BuildDeck;
+
+/// <summary>
+/// /build_deck/buy response. reward_list items use reward_id/reward_num (driven by
+/// PlayerStaticData.UpdateHaveUserGoodsNumByJsonData with POST-STATE-TOTAL semantics);
+/// series_rewards items use reward_detail_id/reward_number — different naming, intentional.
+/// </summary>
+[MessagePackObject]
+public class BuildDeckBuyResponse
+{
+    [JsonPropertyName("reward_list")]
+    [Key("reward_list")]
+    public List<RewardListEntry> RewardList { get; set; } = new();
+
+    [JsonPropertyName("series_rewards")]
+    [Key("series_rewards")]
+    public List<BuildDeckProductRewardDto> SeriesRewards { get; set; } = new();
+}