Feature request: Add docker-cli to be able run docker commands

[ajyey]

Please consider adding the Docker CLI (docker-cli) to the image so that the container can interact with the host's Docker daemon when /var/run/docker.sock is mounted.

This would make it possible to perform docker commands in the pre/post backup hooks.

I'm using this image in my setup:

• My homelab services are defined via Docker Compose.
• Some services use named volumes so I'd like to stop the containers before backing up to ensure data consistency.
• I want to use the pre/post hook scripts to stop and start specific containers (using docker) as part of the backup flow.

Let me know if you'd like me to open a PR for this. Thanks!

[ajyey]

Created PR #99 - feel free to give it a look