s.Cam.cullingMask = ~(1 << overlayLayer);          // Base 相机不画“手持物”层
if (s.Panel == 0) return;

// 叠加相机：只画手持物这一层，挂到 Base 相机的 Stack 里
var go = new GameObject("Overlay Camera");
go.transform.SetPositionAndRotation(s.Cam.transform.position, s.Cam.transform.rotation);
var cam = go.AddComponent<Camera>();
cam.fieldOfView = s.Cam.fieldOfView;
cam.nearClipPlane = 0.05f;
cam.aspect = 640f / 420f;
cam.cullingMask = 1 << overlayLayer;
var data = go.AddComponent<UniversalAdditionalCameraData>();
data.renderType = CameraRenderType.Overlay;
// clearDepth 在 URP 14 里只有 getter，Inspector 上的 Clear Depth 勾选框对应序列化字段 m_ClearDepth
var so = new SerializedObject(data);
so.FindProperty("m_ClearDepth").boolValue = s.Panel == 2;   // 面板 1 不清深度，面板 2 清深度
so.ApplyModifiedPropertiesWithoutUndo();
s.CamData.cameraStack.Add(cam);

var item = s.Knot(s.Lit(new Color(1f, 0.6f, 0.15f), 1f, 0.8f), Vector3.zero, 0.3f);
item.layer = overlayLayer;
item.transform.SetParent(s.Cam.transform, false);
item.transform.localPosition = new Vector3(0.36f, -0.2f, 1.25f);
item.transform.localRotation = Quaternion.Euler(20, 40, 0);