Implements detection of rate limiting in WHOIS and RDAP responses in WhoisService, tracks last error type, and exposes methods to check and clear rate limit errors. Updates check_domains.php to queue domains that fail due to rate limits for retry with exponential backoff, grouped by TLD to avoid repeated rate limiting. Adds statistics and logging for retries and successful retry attempts, and introduces delays between checks and retries to reduce the likelihood of hitting rate limits.
bcd956a495