feat(battle-node): NetworkBattleUri / EmitCategory enums and MsgEnvelope record

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

SVSim.BattleNode/Protocol/NetworkBattleUri.cs

@@ -0,0 +1,46 @@
+namespace SVSim.BattleNode.Protocol;
+
+/// <summary>
+/// Discriminator for every msg/synchronize envelope. Wire form is the bare member name
+/// (case-sensitive). See docs/api-spec/in-battle/enums.md.
+/// </summary>
+public enum NetworkBattleUri
+{
+    None,
+    Resume,
+    Retry,
+    InitNetwork,
+    InitBattle,
+    InitRoomBattle,
+    Matched,
+    Loaded,
+    Deal,
+    Swap,
+    Ready,
+    TurnStart,
+    TurnEndActions,
+    TurnEnd,
+    TurnEndFinal,
+    PlayActions,
+    BattleStart,
+    BattleFinish,
+    ChatStamp,
+    Gungnir,
+    Echo,
+    Retire,
+    OppoDisconnect,
+    End,
+    Judge,
+    Touch,
+    SelectSkill,
+    SelectObject,
+    SlideObject,
+    TurnEndReady,
+    RecoveryStart,
+    RecoveryEnd,
+    JudgeResult,
+    Maintenance,
+    ReplayFinish,
+    Kill,
+    Watch,
+}