Copying a PDF from one DA site to another hlx6 sites fails

Steps to reproduce:
1) Navigate to a site / path that contains a PDF
2) Select the PDF and copy it (without downloading it)
3) Navigate to another site / folder (that is on hlx6 / api.aem.live)
4) Paste from the UI

Actual behaviour:
- The list view shows the pasted PDF
- It cannot be previewed (fails with not found)
- After a reload the entry is gone from the list view

Expected behavior:
- The copy&paste should work

Context:
- When pasting an API call is made to admin.da.live even if the project is on hlx6 / api.aem.live

Start by tracing the UI paste flow for PDFs and the API request made during paste, paying particular attention to the admin.da.live call when the destination uses hlx6 or api.aem.live. Reproduce the steps with a PDF, then verify that the pasted item previews successfully and remains in the list after reload.

Written by the indexing model from the issue text.