Alright, I can do some feedback here if you like
First: Great idea about replacing the actual background with a flavor image from a module / save game / etc. Not sure why I didn't think of that, clever!
Second: As you might have noticed the preview image on its own isn't a very big item and can't really fill a whole summer. I'll give roughly the same advice I gave another student interested in that item recently.
1) Build a new module detail UI screen. While you're on the "Modules" screen add a "Details" button that'll open the module detail screen with extra details on the selected module. This is where I was going to suggest putting an optional image/logo/etc from the module, but you're right that just switching the background (maybe with some partial transparency within the detail frame) would be way better. For details you can expand the fields in use in module.txt to cover more stuff, like splitting the detail into a summary and a long form description. Put the short version on the Modules screen and the long version on the Detail screen. You could add an author(s) field with optional links to their GitHub or whatever else. You could also prepare a spot there for
module configuration something we've needed for a long time. That could simply be a set of config properties the author wants to support and expose for a user to fine-tune the module in some way.
2) In a very similar vein do the same for saved worlds. Rather than just have the screen where you can select a game and load it add a button for "Details" and open up a detail screen triggering an image, a list of which modules are active in that world, what age is it, what was the time of day when you logged out, maybe a map of
where you logged out, and so on. This would be a great spot to change which modules are actually active - allow the user to add new ones and so on. Check out a saved world's files and you should find a module list in a manifest file. This might be a bit trickier to get to work but it would be a good thing to cover later on in the work period.
Roughly I'd focus on working out the initial preview image and the base module detail screen month 1, add in module configuration options month 2, and repeat that for a save game detail screen for month 3.
Check out the PolyWorld module. When you enable it and pick "Island World" during world creation / load the module actually replaces the active background. So doing that with an image loaded from a module (which is in fact the case for PolyWorld) should be fairly straight forward.
