perf(async): remove blocking std::process::Command from async paths

Every production process spawn reachable from a tokio worker now uses
tokio::process: the install path's podman-port probe, the dependencies
disk check, factory-reset restart, config host-IP detection, the
orchestrator's host-facts helpers (resolve_dynamic_env and its call
sites made async to carry it through), and AutoRuntime's podman/docker
probes.

The FIPS transport probe is the special case: is_available() is a sync
trait method called from async route(), so instead of blocking ~50ms
on systemctl per stale-cache hit it now serves the cached value and
refreshes on a background thread (stale-while-revalidate) — bounded
staleness, zero stalled workers.

§C of the 1.8.0 hardening plan; container/transport/config/package
suites green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

core/archipelago/src/api/rpc/system/handlers.rs

@@ -575,7 +575,7 @@ impl RpcHandler {
         // Restart the service via systemd
         tokio::spawn(async {
             tokio::time::sleep(std::time::Duration::from_secs(2)).await;
-            let _ = std::process::Command::new("sudo")
+            let _ = tokio::process::Command::new("sudo")
                 .args(["systemctl", "restart", "archipelago"])
                 .spawn();
         });