feat(mypage): /mypage/finish_battle (returns check=0 — no in-flight state yet)

SVSim.EmulatedEntrypoint/Models/Dtos/Requests/MyPage/MyPageFinishBattleRequest.cs

@@ -0,0 +1,14 @@
+using MessagePack;
+using System.Text.Json.Serialization;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Requests.MyPage;
+
+[MessagePackObject]
+public class MyPageFinishBattleRequest : BaseRequest
+{
+    // Wire key is uppercase "SDTRB" — verbatim from
+    // PlayerPrefsWrapper.SELF_DISCONNECT_OPEN_STATUS_TO_REPLACE_LOG.
+    [JsonPropertyName("SDTRB")]
+    [Key("SDTRB")]
+    public int Sdtrb { get; set; }
+}

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/MyPage/MyPageFinishBattleResponse.cs

@@ -0,0 +1,17 @@
+using MessagePack;
+using System.Text.Json.Serialization;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses.MyPage;
+
+/// <summary>
+/// Spec source: docs/api-spec/endpoints/post-login/mypage-finish-battle.md.
+/// We always emit check_unfinished_battle=0 because no in-flight battle state
+/// is tracked server-side yet. When that lands, branch to is_win + class/rank refresh.
+/// </summary>
+[MessagePackObject]
+public class MyPageFinishBattleResponse
+{
+    [JsonPropertyName("check_unfinished_battle")]
+    [Key("check_unfinished_battle")]
+    public int CheckUnfinishedBattle { get; set; }
+}