chore: Assets 디렉토리 구조 정리 및 네이밍 컨벤션 적용

- Assets/_Game/ 하위로 게임 에셋 통합
- External/ 패키지 벤더별 분류 (Synty, Animations, UI)
- 에셋 네이밍 컨벤션 확립 및 적용
  (Data_Skill_, Data_SkillEffect_, Prefab_, Anim_, Model_, BT_ 등)
- pre-commit hook으로 네이밍 컨벤션 자동 검사 추가
- RESTRUCTURE_CHECKLIST.md 작성

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Assets/External/Tools/SyntyPackageHelper/Editor/SyntyPackageHelperConfig.cs

@@ -0,0 +1,27 @@
+#if UNITY_EDITOR
+using UnityEngine;
+using UnityEditor;
+
+[CustomEditor(typeof(SyntyPackageHelperConfig))]
+public class ExamplePackConfigLoaderEditor : Editor
+{
+    public override void OnInspectorGUI()
+    {
+        DrawDefaultInspector();
+
+        SyntyPackageHelperConfig config = (SyntyPackageHelperConfig)target;
+        if (GUILayout.Button("Install Packages"))
+        {
+            SyntyPackageHelper.ProcessConfigs(new SyntyPackageHelperConfig[] { config }, true);
+        }
+    }
+}
+
+[CreateAssetMenu(fileName = "SyntyPackageHelperConfig", menuName = "Scriptable Objects/SyntyPackageHelperConfig")]
+public class SyntyPackageHelperConfig : ScriptableObject
+{
+    public string assetPackDisplayName;
+    public string[] packageIds;
+    public bool hasPromptedUser;
+}
+#endif