Auto-pull local models

[dgageot]

When running cagent with a local model that hasn’t been pulled yet, I think it should auto-pull to be more sharable.

(Reported by a Docker Captain)

[krissetto]

Should we maybe do this via a sort of confirmation prompt, or just yolo it and we find a way to share some progress status? some models can take a long time to download

e.g.

To run this agent i need to download <some_model>. Doing so will use <some_disk_space>.
Would you like to proceed?

Then we could update the UI with the current progress or something before starting the agent