* fix: don't treat refused or self-redirected responses as not-found
401 and 429 fell through to the checkType branch, where any non-2xx code means the username is free, so blocked and rate-limited requests were reported as confirmed absences; they now return errors, Vercel's Security Checkpoint joins the bot-protection markers, and a self-redirect that carries Set-Cookie is retried once instead of read as an absence.
* Fix site checks: 16 sites, 3 fixed, 12 disabled, 1 dead deleted
* docs: note that the joyreactor self-redirect is intermittent
