feat(crawler): CRAWLER_ALLOW_ANY_HOST bypasses the host allowlist (0.44.0)

Operators whose sources shard images across numbered CDN subdomains
can't pre-enumerate every host in CRAWLER_DOWNLOAD_ALLOWLIST. The new
flag short-circuits the host check in DownloadAllowlist::contains
while leaving scheme, localhost, and private-IP defenses in
is_safe_url untouched — scraped URLs pointing at 10.x /
169.254.169.254 / file:// stay refused. Default is false; fail-closed
posture is preserved unless the operator opts in. Wired into both the
server (config::build_download_allowlist) and the bin/crawler.rs
one-shot.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/Cargo.lock

@@ -1470,7 +1470,7 @@ checksum = "c41e0c4fef86961ac6d6f8a82609f55f31b05e4fce149ac5710e439df7619ba4"
 
 [[package]]
 name = "mangalord"
-version = "0.43.1"
+version = "0.44.0"
 dependencies = [
  "anyhow",
  "argon2",