[Feature Request] Add static background image to visualization of the prod calculator

[Paul210132]

Hi ! first of all thanks for all the hard work you've put into the tools you've developed, they're pretty dope and exhaustive and I never NOT plan my factory with their help.

I'd like to suggest that users could have the option to insert a custom static image as a background for the visualization tab of the production calculator, this way I could for instance drag and drop a screenshot of the map in the area of my choice and move the draggable nodes on the areas of the map where I wish to build. This way no need to toggle back and forth between planning conceptually and geographically.