feat(battle-node): add JudgeBody record for opponent turn-end Judge push

Mirrors OpponentTurnStartBody — JsonPropertyName-cased spin + resultCode
(default 1). First piece of the v1.2 three-frame turn-end burst; nothing
references it yet.

SVSim.BattleNode/Protocol/Bodies/JudgeBody.cs

@@ -0,0 +1,7 @@
+using System.Text.Json.Serialization;
+
+namespace SVSim.BattleNode.Protocol.Bodies;
+
+public sealed record JudgeBody(
+    [property: JsonPropertyName("spin")] int Spin,
+    [property: JsonPropertyName("resultCode")] int ResultCode = 1) : IMsgBody;