Disabling the Docker cache greatly increases the time it takes to
rebuild an image during development.

The `docker build` command requires specifying a directory in
addition to the Dockerfile.

These changes add makefile targets for building the golangci-lint tool
and to run it.
This makes it very easy to get and run the linter, and thus adding it to
the CI.

We have an official name now, so this patch adds the respective changes
to the frontend.

We need convenient and consistent ways for running the linter, so these
changes add makefile targets and npm scripts for that.

The backend and frontend should be self-contained in their repective
paths as much as possible. The frontend was already in a good state but
the backend had the go.{mod,sum} files outside of the backend folder.

These changes move the backend/server.go into a new backend/cmd/ folder,
the mentioned go module related files into the backend folder, and
update the Makefile to reflect those changes.

These changes add a dockerfile and a makefile target for building a
Docker image.