【修复】修复长期持有tcp连接未关闭

【修复】修复生成新的acme账号时有概率覆盖所有账号
【修复】修复新旧let账号不统一的兼容性问题

backend/internal/cert/apply/apply.go

@@ -495,7 +495,8 @@ func Apply(cfg map[string]any, logger *public.Logger) (map[string]any, error) {
 		}
 		httpClient = &http.Client{
 			Transport: &http.Transport{
-				Proxy: http.ProxyURL(proxyURL),
+				Proxy:             http.ProxyURL(proxyURL),
+				DisableKeepAlives: true,
 			},
 			Timeout: 30 * time.Second,
 		}