fix(enemy): 应用 Task 3 代码审查意见

补上池化路径的防重复记忆重置——ResetRepeatMemory 此前文档承诺了
「对象池复用时清除」却无任何调用点，而它要取代的 BossBase.LastUsedSkillId
恰好在 OnSpawn 里有重置。放 EnemyBase.OnSpawn 以覆盖全部池化敌人。

折扣系数改为每次选招前刷新，与 attackSelectionMode 的读取时机对齐——
此前策划在播放模式下调系数无效、调模式却立即生效，容易误判为功能没生效。
默认值收敛为 EnemyAttackSelector.DefaultAntiRepeatFactor 单一常量。

测试：IneligiblePrevious 用例改用系数 0.5——原先用 0 时，把折扣错写在
eligibility 归零之前也照样通过，是个永远不会失败的测试；统计用例边界由
7σ 收紧到 5σ 使其真正验证该系数；补 ResetRepeatMemory 的确定性用例、
系数 1.0 无惩罚、三候选三条。

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Assets/_Game/Scripts/Enemies/Abilities/EnemyAttackSelector.cs

@@ -9,23 +9,35 @@ namespace BaseGames.Enemies.Abilities
     /// </summary>
     public sealed class EnemyAttackSelector
     {
+        /// <summary>防重复折扣系数的默认值。EnemyStatsSO 字段初值与 EnemyBase 的兜底分支共用此常量。</summary>
+        public const float DefaultAntiRepeatFactor = 0.3f;
+
         private readonly List<IAttackCandidate> _candidates;
         // 权重缓冲区（与 _candidates 等长，每次选招复用）：避免每次选招 new List 造成 GC
         private readonly List<float> _weightBuf;
         // 防重复折扣系数：0 = 有替代时绝不连续重复，1 = 不惩罚
-        private readonly float _antiRepeatFactor;
+        private float _antiRepeatFactor;
 
         private IAttackCandidate _lastPicked;
 
-        public EnemyAttackSelector(IEnumerable<IAttackCandidate> candidates, float antiRepeatFactor = 0.3f)
+        public EnemyAttackSelector(IEnumerable<IAttackCandidate> candidates,
+                                   float antiRepeatFactor = DefaultAntiRepeatFactor)
         {
-            _candidates       = new List<IAttackCandidate>(candidates);
-            _weightBuf        = new List<float>(_candidates.Count);
-            _antiRepeatFactor = Mathf.Clamp01(antiRepeatFactor);
+            _candidates      = new List<IAttackCandidate>(candidates);
+            _weightBuf       = new List<float>(_candidates.Count);
+            AntiRepeatFactor = antiRepeatFactor; // 经属性赋值，夹紧逻辑只有一处
         }
 
         public int Count => _candidates.Count;
 
+        /// <summary>防重复折扣系数。与 attackSelectionMode 一样每次选招前由调用方刷新，
+        /// 使策划在播放模式下调参能立即生效。</summary>
+        public float AntiRepeatFactor
+        {
+            get => _antiRepeatFactor;
+            set => _antiRepeatFactor = Mathf.Clamp01(value);
+        }
+
         /// <summary>上一次实际选中的招（防重复折扣的作用对象；供测试与调试面板读取）。</summary>
         public IAttackCandidate LastPicked => _lastPicked;