Glossary screenshots enhancement

### Describe the problem

The current Glossary feature allows the upload of contextual images. However, to view these images, one must click into the corresponding Glossary entry, which is cumbersome. This is particularly problematic for specialized terms such as personal names, equipment names, or other texts that require translators to understand the context, as they must click on the Glossary and wait for it to load to see what it is (via images uploaded by developers).

### Describe the solution you would like

Therefore, I hope for two improvements:

The Glossary should support external URLs instead of requiring file uploads, allowing for simpler integration with our CDN and image servers.
On the translation interface, Glossary terms that are highlighted should show a pop-up with images when hovered over (if available), and the Glossary sidebar should ideally display image thumbnails as well.

### Describe alternatives you have considered

_No response_

### Screenshots

_No response_

### Additional context

_No response_