closes: https://github.com/TryGhost/Ghost/issues/13739
- Ghost cannot write to the core folder in correctly configured production installations
- Built assets therefore need to be written to the content directory
- Ghost does not overwrite anything in the content folder as part of an upgrade, therefore static files that are provided by Ghost
must still live inside /core
- So as a result, we now have core/frontend/public and content/public
- If we register the serve public file middleware for a file that doesn't exist, this will currently throw an ENOENT error
- Instead, we want to fall back to a standard 404 so that this behaves normally
- This will be useful for the card asset service, where the cards.min.css and cards.min.js files may or may not exist
- we're slowly trying to draw the lines between the backend and the frontend correctly
- these files deal only with serving the frontend so they should live there
- there are lots of mixed requires in these files, so having them in the right place makes that clear
