[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/FindTargetAction.cs

@@ -0,0 +1,35 @@
+using System;
+using Unity.Behavior;
+using UnityEngine;
+using Action = Unity.Behavior.Action;
+using Unity.Properties;
+
+[Serializable, GeneratePropertyBag]
+[NodeDescription(name: "FindTarget", story: "[타겟] 탐색", category: "Action", id: "bb947540549026f3c5625c6d19213311")]
+public partial class FindTargetAction : Action
+{
+    [SerializeReference]
+    public BlackboardVariable<GameObject> Target;
+    
+    [SerializeReference]
+    public BlackboardVariable<string> Tag = new BlackboardVariable<string>("Player");
+
+    protected override Status OnStart()
+    {
+        if (Tag.Value == null || string.IsNullOrEmpty(Tag.Value))
+        {
+            return Status.Failure;
+        }
+
+        GameObject foundTarget = GameObject.FindGameObjectWithTag(Tag.Value);
+        
+        if (foundTarget == null)
+        {
+            return Status.Failure;
+        }
+
+        Target.Value = foundTarget;
+        return Status.Success;
+    }
+}
+