PEACE portal: document link has no return option

This is a problem in the embedded search interface on [PEACE portal](https://peace.sites.uu.nl/). When you click the "link" for a document to open it in a separate page, the document opens but there is no link back to the search interface.

If Textcavator is not embedded, you can use the "back" navigation in the browser to go back to your query. You can also do that within an iframe, but it's less obvious, so the document page can feel like a dead end with no way to go back.

Possible solutions:

1. If the page is embedded, hide the document link (you can still open the popup).
2. If the page is embedded, set `target="_blank"` to open the document in a new tab.
3. Add link back to your query in the document page.

Options 1 and 2 are trivial to implement. Option 2 would fit with the original intention of the page (namely as a way to bookmark/reference/share individual documents.)

Option 3 is more complicated, because the document page does not "remember" the user query. Storing the query might be useful for some other features, though, such as showing highlights.

Start by locating the embedded search interface and the document-link handling described in the issue, then reproduce the behavior on the PEACE portal in an iframe. Compare the three proposed navigation options and confirm that the chosen behavior preserves direct document sharing while giving embedded users a clear way back to their query.

Written by the indexing model from the issue text.