chore: initial skeleton

- docs/architecture.md: native rewrite plan (5 services + control plane,
  Active-Active cluster like nmg, Floating-IP for HTTP ingress)
- cmd/edgeguard-{api,scheduler,ctl}: minimal Gin + CLI stubs
- packaging/debian/edgeguard-{api,ui,meta}: control + maintainer scripts
- deploy/systemd/edgeguard-api.service + edgeguard-scheduler.service
  with hardening defaults
- Makefile: build / cross-compile (amd64+arm64) / deb / publish targets
- scripts/install.sh + scripts/apt-repo/build-package.sh stubs

cmd/edgeguard-ctl/main.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+var version = "0.0.1-dev"
+
+const usage = `edgeguard-ctl — EdgeGuard CLI
+
+Usage:
+  edgeguard-ctl <command> [args]
+
+Commands:
+  version              Print version
+  initdb               Initialise PostgreSQL database and user (idempotent)
+  migrate up           Apply pending migrations
+  migrate down         Roll back last migration (dev only)
+  cluster-join         Join an existing cluster (--from URL --token TOKEN)
+  cluster-leave        Leave the cluster cleanly
+  promote              Promote this node's PG to primary
+  dump-config          Print effective config to stdout
+`
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Fprint(os.Stderr, usage)
+		os.Exit(2)
+	}
+	switch os.Args[1] {
+	case "version":
+		fmt.Println(version)
+	case "-h", "--help", "help":
+		fmt.Print(usage)
+	default:
+		fmt.Fprintf(os.Stderr, "edgeguard-ctl: command %q not yet implemented\n", os.Args[1])
+		os.Exit(2)
+	}
+}