Add vips-ffm to Imagery section

[lopcode]

Adds vips-ffm to the Imagery section.

My reasons for adding:

• There are no other libraries listed that use libvips, which is quite popular for image processing
• It's a novel usage of JDK 22's Foreign Function & Memory (FFM) API
• Performance for image processing is significantly better than existing options
• There are already some quite large users of the library

I didn't make libvips a link in the entry, as if you're looking at imagery options libvips is probably known to you, and I couldn't see any other examples of linking out in descriptions.

I created the library, but still feel it meets the requirements noted in CONTRIBUTING - of course feel free to view critically.