feat: add repeatable kubeadm rebuild and reset scripts

nixos/kubeadm/README.md

@@ -90,6 +90,31 @@ kubectl get nodes -o wide
 kubectl -n kube-system get pods -o wide
 ```
 
+## Repeatable rebuild flow (recommended)
+
+1. Copy and edit inventory:
+
+```bash
+cp ./scripts/inventory.example.env ./scripts/inventory.env
+$EDITOR ./scripts/inventory.env
+```
+
+2. Rebuild all nodes and bootstrap cluster:
+
+```bash
+./scripts/rebuild-and-bootstrap.sh
+```
+
+3. If you only want to reset Kubernetes state on existing VMs:
+
+```bash
+./scripts/reset-cluster-nodes.sh
+```
+
+For a full nuke/recreate lifecycle:
+- run Terraform destroy/apply for VMs first,
+- then run `./scripts/rebuild-and-bootstrap.sh` again.
+
 ## Notes
 
 - Scripts are intentionally manual-triggered (predictable for homelab bring-up).