These are the changes I made to get it running locally

I'm going to keep my fork around for giving demos on my machine for now, but I thought I'd send you a pull request so you can consider making some of the changes yourself. I had to guess a bit regarding the exact commits to use for git dependencies in package.json - I just went for commits around the same date that you last significantly modified hoodie-invoice. The rest of the changes are just copying the front-end files over from the noBackend-app-invoice repository and updating the paths (so it uses the local _api instead of the one hosted on jit.su etc).