[Internal] IronPDF stamp positioned behind the existing stamps from Adobe

Our developer investigated this issue and find out as follows:

1. The stamp added using Adobe is classified as an Image Annotation. Annotations are always displayed on top, which is why our stamp appears behind it.

2. Flattening the document before applying the stamp can resolve this issue.

3. However, we do not automatically flatten documents internally before stamping, as this approach may not be suitable for other customers with different requirements.

Therefore, we decided to create a feature request to implement the Image Annotation, which could align with this kind of use case.