refactor(battle-node): replace int IsSelf with CardOwner enum on mined-token tuples

MineAddOps/MineChoicePicks/MineCopyTokens return types and all
extraction casts changed from int to CardOwner. The 4 routing
comparisons in BattleSessionState now read isSelf == CardOwner.Self
instead of isSelf == 1.

No wire or behavioral change — CardOwner was already in use on the
wire-facing side (OppoTargetEntry, UnapprovedCardEntry); this extends
it to the internal mining path so the bare-int transpose risk is gone.

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

SVSim.UnitTests/BattleNode/Integration/CaptureConformanceTests.cs

@@ -414,7 +414,7 @@ public class CaptureConformanceTests
             .MineCopyTokens(orderList, new Dictionary<int, long>(), otherMap)
             .ToList();
 
-        Assert.That(mined, Is.EquivalentTo(new[] { (49, 123_456_789L, 0) }));
+        Assert.That(mined, Is.EquivalentTo(new[] { (49, 123_456_789L, CardOwner.Opponent) }));
     }
 
     [Test]