* support running backend + frontend together on k8s
* split nginx container into separate frontend service, which uses nignx-base image and the static frontend files
* add nginx-based frontend image to docker-compose build (for building only, docker-based combined deployment not yet supported)
* backend:
- fix paths for email templates
- chart: support '--set backend_only=1' and '--set frontend_only=1' to only force deploy one or the other
- run backend from root /api in uvicorn
