Putting this online, in case anyone wants to contribute a fix / change. Will do my best to integrate it. The code has been running on an old server for years untouched, and I barely remember how it works, so probably best to keep any changes minimal. If you want to do something more substantial, feel free to copy any code / ideas and start something new.
This was the first ever AngularJS app I wrote, many years ago, so go easy. It is only the front-end. Open-sourcing (and even changing) the backend would be trickier (and even more embarassing), but I might be persuadable.
Enjoy!