feat: add docker setup for local testing

[MarcCon]

This PR introduces a Docker demo setup for running ERPNext with our custom ALYF apps. It is based on the Docker Workflow PR which provides the custom image used in this setup. #77

Whats Included:

env.example:

Contains configuration values such as site name, database credentials, and the link to the custom Docker image.

docker-compose.yml:

A single Docker Compose file that combines the base configuration and some overrides from the frappe_docker repository.
It automatically creates a new site and installs all the ALYF custom apps on it.

Note:
During setup, the database user must be granted access from all hosts ('%') manually. Without this, connections between Docker containers to the database will fail. This solution is based on this: docker-library/mysql#275
Maybe there is a cleaner way than embedding SQL in the compose file.

In the future, we could also provide a production setup.

[revant]

Optional Checks

• https://github.com/frappe/frappe_docker/blob/main/.github/workflows/docker-build-push.yml (starts a compose and does some basic rest api checks using pytest)
• bench easy-install is using compose, it checks for the script and compose like this https://github.com/frappe/bench/blob/develop/.github/workflows/easy-install.yml

[MarcCon]

Thanks for the suggestions. I think it’s fine for now as long as we make the image available for testing purposes. In the future we can integrate it into our production setup.