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.

internal/web/embed.go

@@ -4,3 +4,6 @@ import "embed"
 
 //go:embed static/*
 var Static embed.FS
+
+//go:embed register/*.tmpl
+var Register embed.FS