Fix redis data permissions that prevent startup

[steveswinsburg]

Summary

The current main branch of inferno-template does not startup due to a redis data permission error.
The key error lines are:

redis-1  | 1:M 13 Nov 2025 03:51:34.612 # Can't open or create append-only dir appendonlydir: Permission denied
redis-1 exited with code 1

This then causes a series of startup failures which ultimately prevent the application from running.

The full error log is attached:
error-log.txt

The key issue is that Redis is trying to write to a host-mounted directory but doesn't have the proper permissions.

This has been fixed by changing the way the redis data directory is defined to be using a named Docker volume with a specific user to avoid host filesystem permission conflicts.

I also removed the obsolete version attribute from the docker-compose yamls.

Testing Guidance

1. Running the commands ./setup.sh and then ./run.sh should start the application without error.
2. Navigating to http://localhost should present the inferno application.

[karlnaden]

I've confirmed that this works and seems correct in the Docker case, but I'm not sure what the impact will be when run in developer mode where the files are currently on the local file system and now will be in a Docker volume. Two options:

1. Provide details on the impact of this change when run in development mode and testing guidance for that case, or
2. Update so that the docker volume for redis is only used in the Docker case. This should be possible by leaving docker-compose.background.yml alone and only updating docker-compose.yml