fix: improve domain availability detection

- Add 'Status: connect' pattern to detect registered domains (fixes .com.de)
- Add 'nserver:' and 'changed:' to registration indicators for CentralNic responses
- Return unavailable for domains with invalid/unsupported TLDs instead of false positive

fix: remove .pro TLD - registry no longer provides WHOIS service

fix: detect server busy and rate limit responses as errors

handle tld not supported errors

availability bugfix

fix: .de domain availability detection

- Fix false positive for registered .de domains with 'Status: connect'
- Add TLD-specific pattern for .de available domains
- Add registration indicator logic for .de domains
- Add comprehensive test cases for .de domain scenarios
- Improve overall TLD-specific detection accuracy

availablity keyword bugfix

complete enhanced domain availability detection integration

implemented enhanced domain availability detection with 6-layer valid…

…ation system

updated ir extensions