feat(01-03): add location hierarchy provisioning and provision CLI script

- ProvisionLocationHierarchy: idempotent Site/Location/Rack creation
- ensureSite/ensureLocation/ensureRack using go-netbox v4 typed requests
- CheckNetBoxInventoryPlugin via /api/plugins/ endpoint
- scripts/provision-netbox.go CLI with go:build ignore tag

scripts/provision-netbox.go

@@ -0,0 +1,57 @@
+//go:build ignore
+
+// Run with: go run scripts/provision-netbox.go
+// Provisions NetBox with all HWLab custom fields and location hierarchy.
+// Reads HWLAB_NETBOX_URL and HWLAB_NETBOX_TOKEN from environment (.env auto-loaded).
+
+package main
+
+import (
+	"context"
+	"log"
+	"os"
+
+	"github.com/joho/godotenv"
+
+	"git.georgsen.dk/hwlab/internal/netbox"
+)
+
+func main() {
+	// Load .env
+	if err := godotenv.Load(); err != nil {
+		log.Printf("no .env file: %v", err)
+	}
+
+	url := os.Getenv("HWLAB_NETBOX_URL")
+	token := os.Getenv("HWLAB_NETBOX_TOKEN")
+
+	if url == "" || token == "" {
+		log.Fatal("HWLAB_NETBOX_URL and HWLAB_NETBOX_TOKEN must be set")
+	}
+
+	client, err := netbox.NewClient(url, token)
+	if err != nil {
+		log.Fatalf("netbox client: %v", err)
+	}
+
+	ctx := context.Background()
+
+	log.Println("Provisioning NetBox...")
+	if err := client.Provision(ctx); err != nil {
+		log.Fatalf("provision: %v", err)
+	}
+
+	// Check netbox-inventory plugin (NB-03)
+	ok, err := client.CheckNetBoxInventoryPlugin(ctx)
+	if err != nil {
+		log.Printf("plugin check error: %v", err)
+	} else if ok {
+		log.Println("netbox-inventory plugin: INSTALLED")
+	} else {
+		log.Println("WARNING: netbox-inventory plugin may not be installed")
+		log.Println("  Manual check: SSH to LXC 130, run: pip show netbox-inventory")
+		log.Println("  Install if missing: pip install netbox-inventory")
+	}
+
+	log.Println("Provisioning complete.")
+}