df command doesn't ensure that standalone runner is available

[silvin-lubecki]

Contrary to list command which calls ensureStandaloneRunnerAvailable (See https://github.com/docker/model-runner/blob/main/cmd/cli/commands/list.go#L51 ), df doesn't and so fails if no model runner backend can be found.

[ericcurtin]

@silvin-lubecki can you explain further? df? Check free disk space?

[doringeman]

Hey @silvin-lubecki, I see what you mean. The list command installs the runner when using Docker CE, but df (and others TBF) don't.
Good catch. I'll clean the code regarding this and ensure it's the same behaviour for all the non *-runner commands.
I'll keep you posted.
Thank you for the report!

[ericcurtin]

I'm just learning about df now, funnily enough it is misnamed... It shows disk usage rather that displaying free disk space... Want to rename it to du @doringeman ? Also generated this PR if it helps but it's pretty simple:

ericcurtin#50