fix(ai): AiRuntime 自转换设为no-op(根治死亡双发Died再入) + EnemyBase.OnSpawn复位brain.enabled + 测试

Switch 对 target==当前态直接 no-op(不重跑Exit/Enter)，循环改为 if(Switch(t))return true;
OnSpawn 复用时恢复被 QuotaManager 裁剪禁用的 brain。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Assets/_Game/Scripts/AI/AiRuntime.cs

@@ -85,7 +85,7 @@ namespace BaseGames.AI
             {
                 var t = globals[i];
                 if (!t.IsEvent && t.Condition(_ctx))
-                    return Switch(t);
+                    { if (Switch(t)) return true; }
             }
 
             var locals = _current.Transitions;
@@ -93,7 +93,7 @@ namespace BaseGames.AI
             {
                 var t = locals[i];
                 if (!t.IsEvent && t.Condition(_ctx))
-                    return Switch(t);
+                    { if (Switch(t)) return true; }
             }
 
             return false;
@@ -106,7 +106,7 @@ namespace BaseGames.AI
             {
                 var t = globals[i];
                 if (t.IsEvent && t.Event.Value == sig)
-                    return Switch(t);
+                    { if (Switch(t)) return true; }
             }
 
             var locals = _current.Transitions;
@@ -114,13 +114,14 @@ namespace BaseGames.AI
             {
                 var t = locals[i];
                 if (t.IsEvent && t.Event.Value == sig)
-                    return Switch(t);
+                    { if (Switch(t)) return true; }
             }
             return false;
         }
 
         bool Switch(Transition t)
         {
+            if (t.Target == _current.Name) return false; // 自转换：no-op，不重跑 Exit/Enter
             var from = _current.Name;
             _current.OnExit?.Invoke(_ctx);
             _current = _graph.GetState(t.Target);