Feature Request: Generate Thumbnail When Uploading Publications on Publications Page

[marta-baraibar]

Description
Currently, when a publication is uploaded on the Publications page, no thumbnail is automatically generated. This results in an inconsistent visual presentation and requires manual intervention to add a thumbnail.

Expected Behavior
When a user uploads a publication, a thumbnail should be automatically generated.
The thumbnail should be derived from the first page of the document (if applicable) or a predefined default image if generation is not possible.
The generated thumbnail should be displayed on the Publications page alongside the publication details.