seqeralabs/nf-canary ? reverse-engineered prompt

Build me a minimal Nextflow workflow that I can use as a smoke test for my infrastructure.

It should run a set of simple checks that prove the basics work, like creating files and folders, passing inputs between steps, moving things around, using a helper script from bin, publishing outputs to an outdir folder, and optionally testing access to a remote file. I also want the workflow to support a GPU check when I ask for it, and a Fusion diagnostics step that only runs when enabled.

Keep it intentionally lightweight and easy to read, with all the test logic in the main workflow and only the configuration needed to make it usable on different systems. I should be able to run it locally with a single command, and also override the container, skip specific tests, or run only one test if needed. If anything needs current Nextflow or Fusion details, look up the latest docs online.