841f1ec2bf
DuckDuckGo intermittently serves a CAPTCHA modal ("Unfortunately, bots
use DuckDuckGo too...") instead of search results. The result selector
matches zero elements on that page, so callers used to get
([]Result{}, nil) — silent empty results that look like "no matches."
Detect the challenge via the BEM class .anomaly-modal__title and return
a typed ErrBlocked so callers can distinguish blocked from no-results
and react (retry, fallback to another engine, surface to user).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>