[METUBE] delete files from disk

[MontejoJorge]

Add variable to delete files from disk when deleting from web ui

https://github.com/alexta69/metube?tab=readme-ov-file#configuration-via-environment-variables

[github-actions]

🎉   Linting finished with no errors or warnings   🎉

Thank you for your submission! This is an automated linter that checks for common issues in pull requests to the Umbrel App Store.

Please review the linting results below and make any necessary changes to your submission.

Linting Results

Severity	File	Description
ℹ️	metube/docker-compose.yml	Potentially using unsafe user in service "metube": The default container user "root" can lead to security vulnerabilities. If you are using the root user, please try to specify a different user (e.g. "1000:1000") in the compose file or try to set the UID/PUID and GID/PGID environment variables to 1000.

Legend

Symbol	Description
❌	Error: This must be resolved before this PR can be merged.
⚠️	Warning: This is highly encouraged to be resolved, but is not strictly mandatory.
ℹ️	Info: This is just for your information.

[nmfretz]

Thanks for this @MontejoJorge. I've been on-the-fence about whether or not to include this env var in the past.

On one hand, the Completed section is kind of just a "downloads history" for videos. The videos are stored in a user's main storage directory on their Umbrel and not in an app directory: /home/umbrel/umbrel/data/storage/downloads/metube. So originally I thought it might be a bit weird to delete the videos permanently with MeTube since you can use the File Browser app to handle all files in Umbrel's main storage... kind of like how most torrent clients work.

But on the other hand, I've seen a few requests now from users who want this functionality within MeTube so let's change it!

I've update MeTube and added a note about the change in the release notes. I've reviewed and tested.