It's an HTTP stub app that returns 200 OK to all requests.
Run the gh workflow run publish-app-production-assets command.
Or, you are able to manually build as follows.
Using docker compose build:
git diff-files --quiet\
Dockerfile.d/go-app.production\
workspace\
compose.yaml && {
local _V=$(git tag --sort=-version:refname | head -n 1)
docker compose build\
--build-arg=GIT_VERSION_TAG=${_V}\
--build-arg=GIT_SHORT_SHA=$(git rev-parse --short HEAD)\
--no-cache go-app.production
}