Install a skill

Install a skill onto this sandbox config's image. Send a zip as multipart form field "file", or JSON {"source":"..."} to pull a public skill. source is one of: "@owner/slug" or a slash-free slug (ClawHub), a github.com / gitlab.com / skills.sh / clawhub / skillhub URL, a ClawHub skills-sh catalog page (https://clawhub.ai/skills-sh/owner/repo/slug), a skills-sh:owner/repo/slug locator, or a direct zip/SKILL.md URL. Bare "owner/slug" is rejected as ambiguous. The source must be readable anonymously. The install boots a sandbox and runs for minutes, so the request is only accepted; follow it via the install-events stream.