[AI] Behavior Actions 시스템 추가

Ultraworked with [Sisyphus](https://github.com/code-yeonggu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

Assets/Scripts/AI/BehaviorActions/Actions/ChaseTargetAction.cs

@@ -0,0 +1,76 @@
+using System;
+using Unity.Behavior;
+using UnityEngine;
+using Action = Unity.Behavior.Action;
+using Unity.Properties;
+
+[Serializable, GeneratePropertyBag]
+[NodeDescription(name: "ChaseTarget", story: "타겟 추적", category: "Action", id: "0889fbb015b8bf414ef569af08bb6868")]
+public partial class ChaseTargetAction : Action
+{
+
+    [SerializeReference]
+    public BlackboardVariable<GameObject> Target;
+    
+    [SerializeReference]
+    public BlackboardVariable<float> Speed = new BlackboardVariable<float>(0f);
+    
+    [SerializeReference]
+    public BlackboardVariable<float> StopDistance = new BlackboardVariable<float>(2f);
+
+    private UnityEngine.AI.NavMeshAgent agent;
+
+    protected override Status OnStart()
+    {
+        if (Target.Value == null)
+        {
+            return Status.Failure;
+        }
+
+        agent = GameObject.GetComponent<UnityEngine.AI.NavMeshAgent>();
+        if (agent == null)
+        {
+            Debug.LogWarning("[ChaseTarget] NavMeshAgent not found");
+            return Status.Failure;
+        }
+
+        // Speed가 0 이하면 NavMeshAgent의 기존 speed 유지 (EnemyData에서 설정한 값)
+        if (Speed.Value > 0f)
+        {
+            agent.speed = Speed.Value;
+        }
+        agent.stoppingDistance = StopDistance.Value;
+        agent.isStopped = false;
+
+        return Status.Running;
+    }
+
+    protected override Status OnUpdate()
+    {
+        if (Target.Value == null)
+        {
+            return Status.Failure;
+        }
+
+        // 이미 사거리 내에 있으면 성공
+        float distance = Vector3.Distance(GameObject.transform.position, Target.Value.transform.position);
+        if (distance <= StopDistance.Value)
+        {
+            agent.isStopped = true;
+            return Status.Success;
+        }
+
+        // 타겟 위치로 이동
+        agent.SetDestination(Target.Value.transform.position);
+        return Status.Running;
+    }
+
+    protected override void OnEnd()
+    {
+        if (agent != null)
+        {
+            agent.isStopped = true;
+        }
+    }
+}
+