test(battle-engine M13): HeadlessNetworkBattleMgr constructs headless (construction probe)

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

SVSim.BattleEngine/Rng/HeadlessNetworkBattleMgr.cs

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+using Wizard;
+using Wizard.BattleMgr;
+
+namespace SVSim.BattleEngine.Rng
+{
+    // The headless authoritative NETWORK battle mgr — the emitting twin of HeadlessBattleMgr. Emission
+    // lives on NetworkBattleManagerBase (NetworkBattleSender's ctor demands one), so the M13 emit read
+    // needs this subclass; HeadlessBattleMgr : SingleBattleMgr cannot reach the sender. RNG overrides are
+    // identical to HeadlessBattleMgr (the same BattleManagerBase virtuals + RandomSourceBridge), so the
+    // M14 rand-list emit reuses this mgr unchanged. M13's deterministic card never exercises a roll.
+    public sealed class HeadlessNetworkBattleMgr : NetworkBattleManagerBase
+    {
+        private readonly IRandomSource _rng;
+
+        public HeadlessNetworkBattleMgr(IBattleMgrContentsCreator contentsCreator, IRandomSource rng = null)
+            : base(contentsCreator)
+        {
+            _rng = rng ?? new SeededRandomSource(contentsCreator.RandomSeed);
+        }
+
+        public override int StableRandom(int val)
+        {
+            double unit = _rng.NextUnit();
+            randomResult = unit;
+            return RandomSourceBridge.Range(val, unit);
+        }
+
+        public override double StableRandomDouble()
+        {
+            double unit = _rng.NextUnit();
+            randomResult = unit;
+            return unit;
+        }
+
+        public override int StableRandomOnlySelf(int val) => _rng.NextSelf(val);
+    }
+}