When an instance sits behind a reverse proxy that requires HTTP Basic Auth,
every detection probe (/info, /api/v1/config, /api/v1/stats, /healthcheck,
/config) returns 401 before reaching the real backend, so the type cannot be
identified. Re-throw APIError.unauthorized from each probe instead of
swallowing it, and have detectWithResult convert the first 401 it sees into
DetectionError.basicAuthRequired. Add a basicAuthHeader parameter so the
caller can retry detection after the user provides credentials; if a retry
also returns 401, surface basicAuthInvalid instead.
