HTTP: require a 2xx status line for generate_204 (Cloudflare edge IPs
answered "HTTP/1.1 409" and were marked alive). SOCKS5: require
REP=0x00 granted. SOCKS4: require REP=0x5a. Verified live: CF anycast
samples now dead, real socks5/http stay alive.
Generated with [Devin](https://devin.ai)
Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>