Function probe_cloud 

pub fn probe_cloud() -> CloudInfo

Run vendor probes; parallel when threads are available, serial fallback otherwise.

Join order follows the PROBES precedence list: the first successful probe wins. Each HTTP call uses IMDS_TIMEOUT. Per-vendor threads are only used when crate::thread_util::spawn_named succeeds so EAGAIN under tight PID limits falls back to sequential probes on the caller thread.