feat(battle-node): client-shaped handshake builders for the scripted bot

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

SVSim.UnitTests/BattleNode/Lifecycle/ScriptedLifecycleTests.cs

@@ -166,6 +166,27 @@ public class ScriptedLifecycleTests
             "single-arg overload (non-interactive opponent) keeps the placeholder hand.");
     }
 
+    [Test]
+    public void BuildClientSwap_has_empty_idxList_in_RawBody()
+    {
+        var env = ScriptedLifecycle.BuildClientSwap();
+        Assert.That(env.Uri, Is.EqualTo(NetworkBattleUri.Swap));
+        Assert.That(env.ViewerId, Is.EqualTo(ScriptedLifecycle.FakeOpponentViewerId));
+
+        var raw = (RawBody)env.Body;
+        Assert.That(raw.Entries.ContainsKey("idxList"), Is.True);
+        var idx = (System.Collections.IEnumerable)raw.Entries["idxList"]!;
+        Assert.That(idx.Cast<object>().Count(), Is.EqualTo(0), "bot keeps its dealt hand (empty mulligan).");
+    }
+
+    [Test]
+    public void BuildClientHandshakeFrames_carry_expected_uris()
+    {
+        Assert.That(ScriptedLifecycle.BuildClientInitNetwork().Uri, Is.EqualTo(NetworkBattleUri.InitNetwork));
+        Assert.That(ScriptedLifecycle.BuildClientInitBattle().Uri, Is.EqualTo(NetworkBattleUri.InitBattle));
+        Assert.That(ScriptedLifecycle.BuildClientLoaded().Uri, Is.EqualTo(NetworkBattleUri.Loaded));
+    }
+
     [Test]
     public void BuildOpponentTurnStart_HasUriTurnStartAndSpin()
     {