--from parameter resolution

The -f / --from parameter is resolved in this order:

  1. Git URL: If the value starts with http:// or https://, use it directly
  2. Config name: Match against configured source names
  3. GitHub shorthand: If the value contains / (e.g., ORG/REPO), expand to https://github.com/ORG/REPO.git
  4. Error: If none of the above match, report “source not found”