fix: touchArray描边去实心填充+ping矩形描边基于模型Bounds

- TouchPositionHandler.OnEnable: 设_MainColor.a=0只留描边
- PingClickHandler.CreateBlueOutline: 根据模型meshRenderer.bounds画矩形环
- 去掉圆环硬编码

Assets/Scripts/Interaction/TouchPositionHandler.cs

@@ -22,7 +22,18 @@ public class TouchPositionHandler : MonoBehaviour
     private void OnEnable()
     {
         _meshRenderer = GetComponent<MeshRenderer>();
-        if (_meshRenderer != null) _meshRenderer.enabled = true;
+        if (_meshRenderer != null)
+        {
+            _meshRenderer.enabled = true;
+            // 只显示描边，填充透明
+            var mat = _meshRenderer.material;
+            if (mat != null && mat.HasProperty("_MainColor"))
+            {
+                var c = mat.GetColor("_MainColor");
+                c.a = 0f;
+                mat.SetColor("_MainColor", c);
+            }
+        }
         StopAllCoroutines();
         StartCoroutine(BlinkMesh());
     }