New dockerfile that better automates build

[cooldracula]

previously, we were building the app and then copying the resulting dist folder into our docker image. By adjusting the base image and ensuring it has everything necessary to build our app, we can do it all as part of the docker image building process. This sets us up to more easily create frontend images as part of an automated pipeline.

This PR also adjusts the committed .env.production file. our production single-host setup uses an nginx proxy to direct traffic to the appropriate services. This means that the frontend does not need to have a separate url to talk to the graphql or blob servers, and can just put in a local path. Since this file is not giving any secrets, and is already committed, we can change it to better fit the new setup.

[mplorentz]

@cooldracula is this something you enabled? I don't recall seeing it on a PR before.