Provider-agnostic web-onboarding import: creates (or resolves) the workspace's skill inventory for the given SCM provider — deriving the org-equivalent from the connected integration — and kicks its first scan. Supports GitHub, GitLab, Bitbucket, and the dev-only MockHub; the scan itself is already provider-aware via the inventory's stored provider. Returns 400 when the workspace has no connected integration for the provider, 409 when a scan or analysis is already in flight, 503 when the workflow engine could not accept the scan, and 404 when the onboarding feature flag is off. Returns the inventory id and the dispatched scan index so the UI can navigate to the progress screen. The route only starts the workflow; the scan, persist, and analysis run inside it.