feat(enemy): AiStateFragments 建态原语，新增 AbilityOnce 修死亡态重触发隐患

从 PerceptionStateMachine 的 private static 辅助方法提升为公开原语，供后续
模块化重构（骨架+可插拔模块）与定制 AiScript 复用。新增 AbilityOnce：
只在进入时触发能力、不每帧重触发，修复用 Ability() 驱动死亡态时演出播完
被 Tick 无限重播的隐患（现有 PerceptionStateMachine 因 E001 死亡能力 id
为空未暴露，本次不改它，留待 T11 整体退役）。

Assets/Tests/EditMode/AI/AiStateFragmentsTests.cs

@@ -0,0 +1,68 @@
+using NUnit.Framework;
+using BaseGames.AI;
+using BaseGames.Enemies;
+
+namespace BaseGames.Tests.EditMode.AI
+{
+    public class AiStateFragmentsTests
+    {
+        static AiRuntime Run(System.Action<BrainBuilder> build, FakeAiContext ctx)
+        {
+            var b = new BrainBuilder();
+            b.Entry("S");
+            build(b);
+            return new AiRuntime(b.Build(), ctx);
+        }
+
+        [Test]
+        public void Locomotion_SetsModeOnEnter()
+        {
+            var ctx = new FakeAiContext();
+            Run(b => AiStateFragments.Locomotion(b, "S", LocomotionMode.Patrol), ctx);
+            Assert.AreEqual(LocomotionMode.Patrol, ctx.L.CurrentMode);
+        }
+
+        [Test]
+        public void Locomotion_FaceMode_FacesLastKnown()
+        {
+            var ctx = new FakeAiContext();
+            ctx.S.Last = new UnityEngine.Vector2(3f, 0f);
+            Run(b => AiStateFragments.Locomotion(b, "S", LocomotionMode.Face), ctx);
+            Assert.AreEqual(new UnityEngine.Vector2(3f, 0f), ctx.L.FacedAt);
+        }
+
+        [Test]
+        public void Ability_RetriggersOnTick_WhenNotRunning()
+        {
+            var ctx = new FakeAiContext();
+            var rt = Run(b => AiStateFragments.Ability(b, "S", "atk"), ctx);
+            Assert.AreEqual(1, ctx.C.Used.Count);
+            ctx.C.Running = null;               // 模拟被受击打断
+            rt.Tick(0.1f);
+            Assert.AreEqual(2, ctx.C.Used.Count); // 重新触发
+        }
+
+        [Test]
+        public void AbilityOnce_DoesNotRetrigger()
+        {
+            var ctx = new FakeAiContext();
+            var rt = Run(b => AiStateFragments.AbilityOnce(b, "S", "death"), ctx);
+            Assert.AreEqual(1, ctx.C.Used.Count);
+            ctx.C.Running = null;               // 演出播完
+            rt.Tick(0.1f);
+            rt.Tick(0.1f);
+            Assert.AreEqual(1, ctx.C.Used.Count); // 不重播
+        }
+
+        [Test]
+        public void LostAllZones_TrueOnlyWhenBothZonesEmpty()
+        {
+            var ctx = new FakeAiContext();
+            Assert.IsTrue(AiStateFragments.LostAllZones(ctx));
+            ctx.S.Chase = true;
+            Assert.IsFalse(AiStateFragments.LostAllZones(ctx));
+            ctx.S.Chase = false; ctx.S.Vision = true;
+            Assert.IsFalse(AiStateFragments.LostAllZones(ctx));
+        }
+    }
+}

Assets/Tests/EditMode/AI/AiStateFragmentsTests.cs.meta

@@ -0,0 +1,11 @@
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Assets/Tests/EditMode/AI/Fakes/FakeLocomotion.cs

@@ -11,9 +11,11 @@ namespace BaseGames.Tests.EditMode.AI
         public bool IsMoving { get; set; }
         public void SetMode(LocomotionMode mode) { CurrentMode = mode; Calls.Add("SetMode:" + mode); }
         public void Approach(Transform t) { CurrentMode = LocomotionMode.Approach; Calls.Add("Approach"); }
-        public void Pursue(Vector2 p) { CurrentMode = LocomotionMode.Approach; Calls.Add("Pursue"); }
+        public Vector2 PursuedTo;
+        public void Pursue(Vector2 p) { PursuedTo = p; CurrentMode = LocomotionMode.Approach; Calls.Add("Pursue"); }
         public void MoveTo(Vector2 p) { Calls.Add("MoveTo"); }
-        public void Face(Vector2 p) { CurrentMode = LocomotionMode.Face; Calls.Add("Face"); }
+        public Vector2 FacedAt;
+        public void Face(Vector2 p) { FacedAt = p; CurrentMode = LocomotionMode.Face; Calls.Add("Face"); }
         public void Stop() { CurrentMode = LocomotionMode.Idle; Calls.Add("Stop"); }
     }
 }