Docker Image Variant v2

I would like to do some breaking changes to the docker image. To not break current setups we should start with image versioning. Example (taken from https://github.com/pimcore/docker#versioning): - `ghcr.io/shopware/docker-base:8.3-frankenphp` (current) - `ghcr.io/shopware/docker-base:8.3-frankenphp-v2025.1` (current) - `ghcr.io/shopware/docker-base:8.3-frankenphp-v2025.9` (new one) We deprecate the old image to time X and annoy people to upgrade to the new one. After the period the image tag without the explict versioning roll over to the next one. Suggested changes to v2: - Use Debian based Images because of musl performance issues and using official Node packages - Reduce variation to just: Caddy+PHP-FPM / FrankenPHP and this contains always GRPC / OpenTelemetry to keep it simple - Remove all Shopware related env variables so they can be overwritten by `.env` file. https://github.com/shopware/docker/blob/main/fpm/Dockerfile#L27