Hover SetNameservers retry loop can re-hit throttled signin after cached session rejection #54

During gocodealone-dns domain intent apply for buymywishlist.net, Cloudflare staging was already up to date, but Hover delegation failed after SetNameservers got a login response from the write endpoint. The recovery path revalidated the cached browser session, then forced a fresh signin. Hover returned repeated 429/502 responses and finally a login 401.\n\nExpected: once Hover returns retryable signin throttling, the plugin should persist a cooldown signal in the browser profile so subsequent workflow runs can still reuse a valid cached session but do not immediately post credentials again while Hover is throttling.\n\nObserved run: https://github.com/GoCodeAlone/gocodealone-dns/actions/runs/27503459922\n\nAcceptance:\n- Exhausted retryable browser signin responses are classified distinctly as signin throttling.\n- A profile-local cooldown marker prevents another credential post during the cooldown window.\n- A valid warm session clears the marker.\n- Regression test covers two consecutive login attempts with the same browser profile.