refactor(battlenode): close §A boolean-blindness items (MinedToken, Stock, KeyActionType)

Behavior-preserving; 231 BattleNode tests green.

- MinedToken record struct replaces the transpose-prone (int Idx, long CardId,
  CardOwner IsSelf) tuple returned by KnownListBuilder.Mine*. Positional deconstruct
  keeps the Record*From call sites unchanged.
- enum Stock { Normal, Bypass } replaces the negative `bool noStock` on
  IBattleParticipant.PushAsync and DispatchRoute, threaded through both participants,
  BattleSession, and all handler construction sites.
- enum KeyActionType mirrors the client's SendKeyActionDataManager.KeyActionType;
  the StripKeyActionForOpponent guard compares named values, KeyActionEntry.Type is
  the enum (wire-identical via JsonNumberEnumConverter).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

SVSim.BattleNode/Sessions/IBattleParticipant.cs

@@ -24,9 +24,9 @@ public interface IBattleParticipant : IAsyncDisposable
     /// <summary>Session calls this to deliver a frame from the OTHER participant
     /// (or a server-synthesized broadcast). Real impl: encode + WS-send.
     /// NoOp: swallow.</summary>
-    /// <param name="noStock">True for control frames (BattleFinish, JudgeResult, ack);
-    /// bypasses playSeq assignment + archive.</param>
-    Task PushAsync(MsgEnvelope envelope, bool noStock, CancellationToken ct);
+    /// <param name="stock"><see cref="Stock.Bypass"/> for control frames (BattleFinish, JudgeResult,
+    /// ack) — bypasses playSeq assignment + archive; <see cref="Stock.Normal"/> for gameplay frames.</param>
+    Task PushAsync(MsgEnvelope envelope, Stock stock, CancellationToken ct);
 
     /// <summary>Participant fires this when it has a frame to send TO the session
     /// (its own gameplay action). Real impl: fires on WS recv. NoOp: never fires.</summary>