fix(battle-node): assign turnState per side instead of hardcoding 0

Both PvP clients received turnState:0 ('both go first'). BuildBattleStart
now takes turnState; the Loaded arm assigns 0 to A, 1 to B — no Type check,
correct in Scripted (real player = A = first) and PvP (first arriver first).

Updated three existing BuildBattleStart callers in the test suite to pass
turnState:0 (the param is now required).

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

SVSim.BattleNode/Lifecycle/ScriptedLifecycle.cs

@@ -53,10 +53,10 @@ public static class ScriptedLifecycle
             bid: battleId);
 
     public static MsgEnvelope BuildBattleStart(
-        MatchContext selfCtx, MatchContext oppoCtx, long selfViewerId) =>
+        MatchContext selfCtx, MatchContext oppoCtx, long selfViewerId, int turnState) =>
         EnvelopeForPush(NetworkBattleUri.BattleStart,
             new BattleStartBody(
-                TurnState: 0,    // player goes first
+                TurnState: turnState,    // 0 = this side goes first, 1 = second. Caller decides.
                 BattleType: selfCtx.BattleType,
                 SelfInfo: new BattleStartSelfInfo(
                     Rank: ScriptedProfiles.PlayerRank,