- Add WhoisXML API as Tier 3 fallback (works for ALL 7,500+ TLDs)
- Fix WhoisXML API parsing to check registryData for expiration
- Update README with 3-tier fallback documentation
- Add WHOISXML_API_KEY environment variable
- Successfully tested with gov.bz (previously failing)

Tier 1: RDAP (fast, free, most domains)
Tier 2: python-whois (free, .uk/.ca/.fr/.io/.ai)
Tier 3: WhoisXML API (500 free/month, all TLDs including .bz)