Add quick-register one-liner for target-host registration

Operator pastes `curl -fsSL $ORCH/register/quick.sh | sudo bash` on the
target host (pre-wipe). The script probes MAC + CPU/RAM/disks/NICs/GPUs,
emits an expected-spec YAML, and POSTs to a new LAN-trusted JSON
endpoint /api/v1/hosts. The register page shows the command prefilled
with the orchestrator URL; the manual form moves into a collapsible
"Register manually" disclosure.

cmd/vetting/main.go

@@ -102,6 +102,7 @@ func main() {
 		EventHub:  hub,
 		Runner:    runner,
 		Tiles:     tiles,
+		PublicURL: cfg.Server.PublicURL,
 	}
 
 	agentAPI := &api.Agent{