Operators whose sources shard images across numbered CDN subdomains
(cdn1/cdn2/…) can't realistically pre-enumerate every host in
CRAWLER_DOWNLOAD_ALLOWLIST. The new flag short-circuits the host check
in DownloadAllowlist::contains while leaving the scheme, localhost,
and private-IP defenses in is_safe_url untouched, so scraped URLs
pointing at 10.x / 169.254.169.254 / file:// stay refused.
Wired in both the server (config::build_download_allowlist) and the
one-shot bin/crawler.rs entry point. Default is false — fail-closed
posture is preserved unless the operator opts in.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>