Add docker for production

[arthurpar06]

This PR introduces a Docker stack for production. The stack is based on caddy and serversideup/php-fpm, and it includes multiple containers to support a queue worker, a task runner, and http/https via Caddy.

As part of this update, I removed the sample module (which was unused) since it was installed via composer in the modules folder.

Additionally, this PR allows for the installation of phpVMS by manually creating a .env file and then setting up the first user and airline through the web installer.

Currently, the image is built locally, and some basic folders are mounted for data persistence. However, there are alternative approaches for handling this. A documentation update is planned to outline these options. We also intend to implement GitHub Actions for building this image and distributing it via Docker Hub, for those who prefer not to build the image themselves.

Closes #1815

Roadmap:

• Create a custom image with the extensions we need, Composer, and (maybe) mariadb-client
• Add an "installation" script to run "composer dump-autoload" on the first launch
• Remove sample module
• Create a .env.example file
• Perform real-world testing
• Update installer to support step3 only install
• Build custom image in CI (will be done in another PR)
• Update docs (will be done in another PR)

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