feat: multi-distro support and tagged golden snapshots

Add Alpine, Debian, and Ubuntu rootfs support to `init [distro]`.
Golden snapshots are now namespaced under `golden/<tag>/` so multiple
baselines can coexist. `spawn [tag] [N]` selects which snapshot to
clone from. Systemd-based distros (Debian, Ubuntu) get a fc-net-init
systemd unit; Alpine keeps its inittab-based init.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

main.go

@@ -21,6 +21,7 @@ import (
 	"os"
 	"path/filepath"
 	"runtime"
+	"strconv"
 
 	log "github.com/sirupsen/logrus"
 
@@ -65,15 +66,32 @@ func main() {
 
 	switch os.Args[1] {
 	case "init":
-		fatal(orch.Init())
+		distro := "alpine"
+		if len(os.Args) > 2 {
+			distro = os.Args[2]
+		}
+		fatal(orch.Init(distro))
 	case "golden":
-		fatal(orch.Golden())
+		tag := "default"
+		distro := "alpine"
+		if len(os.Args) > 2 {
+			tag = os.Args[2]
+		}
+		if len(os.Args) > 3 {
+			distro = os.Args[3]
+		}
+		fatal(orch.Golden(tag, distro))
 	case "spawn":
 		n := 1
-		if len(os.Args) > 2 {
-			fmt.Sscanf(os.Args[2], "%d", &n)
+		tag := "default"
+		for _, arg := range os.Args[2:] {
+			if parsed, err := strconv.Atoi(arg); err == nil {
+				n = parsed
+			} else {
+				tag = arg
+			}
 		}
-		fatal(orch.Spawn(n))
+		fatal(orch.Spawn(n, tag))
 	case "status":
 		orch.Status()
 	case "kill":
@@ -98,14 +116,16 @@ func main() {
 		// Internal subcommand: started by spawnOne, runs as a background daemon.
 		fs := flag.NewFlagSet("_console-proxy", flag.ContinueOnError)
 		var id int
+		var tag string
 		var tap string
 		fs.IntVar(&id, "id", 0, "clone ID")
+		fs.StringVar(&tag, "tag", "default", "Golden VM tag")
 		fs.StringVar(&tap, "tap", "", "TAP device name")
 		if err := fs.Parse(os.Args[2:]); err != nil {
 			fmt.Fprintf(os.Stderr, "console-proxy: %v\n", err)
 			os.Exit(1)
 		}
-		fatal(orchestrator.RunConsoleProxy(orchestrator.DefaultConfig(), id, tap))
+		fatal(orchestrator.RunConsoleProxy(orchestrator.DefaultConfig(), id, tap, tag))
 	default:
 		usage()
 		os.Exit(1)
@@ -119,9 +139,9 @@ Flags:
   --dev         log format with source file:line (e.g. file="orchestrator.go:123")
 
 Commands:
-  init          Download kernel + create Alpine rootfs
-  golden        Boot golden VM → pause → snapshot
-  spawn [N]     Restore N clones from golden snapshot (default: 1)
+  init [distro] Download kernel + create distro rootfs (default: alpine, options: alpine, debian, ubuntu)
+  golden [tag] [distro] Boot golden VM → pause → snapshot (default tag: default, default distro: alpine)
+  spawn [tag] [N] Restore N clones from golden snapshot (default tag: default, default N: 1)
   serve [addr]  Start terminal web UI (default: :8080)
   console <id>  Attach to the serial console of a running clone (Ctrl+] to detach)
   status        Show running clones