[2025] Build image upload functionality

[pcraig3]

NOFOs sometimes use images on their cover pages, and then (much more rarely) will include images inline.

The inline images actually come through as data base64 strings, so those ones are more or less okay, but we should create an image upload ability (or maybe we base64 everything) for cover images so that people can manage them themselves.

Right now uploading images is a dev task. Autodeploying from Github has helped with this, but most regular people don't know how to create a pull request.

Once we move to our new infrastructure, we should add image uploading.