fix(openai): quarantine proxies after stream disconnects

deploy/.env.example

@@ -287,6 +287,9 @@ GATEWAY_OPENAI_HTTP2_ALLOW_PROXY_FALLBACK_TO_HTTP1=true
 GATEWAY_OPENAI_HTTP2_FALLBACK_ERROR_THRESHOLD=2
 GATEWAY_OPENAI_HTTP2_FALLBACK_WINDOW_SECONDS=60
 GATEWAY_OPENAI_HTTP2_FALLBACK_TTL_SECONDS=600
+GATEWAY_OPENAI_PROXY_STREAM_CIRCUIT_FAILURE_THRESHOLD=2
+GATEWAY_OPENAI_PROXY_STREAM_CIRCUIT_WINDOW_SECONDS=60
+GATEWAY_OPENAI_PROXY_STREAM_CIRCUIT_TTL_SECONDS=600
 # 上游连接池：每主机最大连接数（默认 1024；流式/HTTP1.1 场景可调大，如 2400/4096）
 GATEWAY_MAX_CONNS_PER_HOST=2048
 # 上游连接池：最大空闲连接总数（默认 2560；账号/代理隔离 + 高并发场景可调大）