fix: pin kubeadm init node identity to flake hostname

Set hostname before init and inject nodeRegistration.name into kubeadm InitConfiguration so cp-1 registers as the expected node (cp-1) instead of inheriting the template hostname. This fixes upload-config/kubelet failures caused by node lookup for k8s-base-template.

nixos/kubeadm/modules/k8s-common.nix

@@ -116,6 +116,7 @@ in
       pod_subnet="${config.terrahome.kubeadm.podSubnet}"
       service_subnet="${config.terrahome.kubeadm.serviceSubnet}"
       domain="${config.terrahome.kubeadm.clusterDomain}"
+      node_name="${config.networking.hostName}"
 
       local_ip_cidr=$(ip -4 -o addr show dev "$iface" | awk 'NR==1 {print $4}')
       if [ -z "''${local_ip_cidr:-}" ]; then
@@ -128,6 +129,9 @@ in
 
       echo "Using control-plane endpoint: $vip:6443"
       echo "Using kube-vip interface: $iface"
+      echo "Using kubeadm node name: $node_name"
+
+      hostnamectl set-hostname "$node_name" || true
 
       rm -f /var/lib/kubelet/config.yaml /var/lib/kubelet/kubeadm-flags.env
 
@@ -155,6 +159,7 @@ in
       apiVersion: kubeadm.k8s.io/v1beta4
       kind: InitConfiguration
       nodeRegistration:
+        name: "KUBEADM_NODE_NAME"
         criSocket: unix:///run/containerd/containerd.sock
       ---
       apiVersion: kubeadm.k8s.io/v1beta4
@@ -178,6 +183,7 @@ in
       sed -i "s|KUBEADM_POD_SUBNET|$pod_subnet|g" /tmp/kubeadm/init-config.yaml
       sed -i "s|KUBEADM_SERVICE_SUBNET|$service_subnet|g" /tmp/kubeadm/init-config.yaml
       sed -i "s|KUBEADM_DNS_DOMAIN|$domain|g" /tmp/kubeadm/init-config.yaml
+      sed -i "s|KUBEADM_NODE_NAME|$node_name|g" /tmp/kubeadm/init-config.yaml
 
       echo "==> Pre-pulling kubeadm images"
       env -i PATH=/run/current-system/sw/bin:/usr/bin:/bin kubeadm config images pull --config /tmp/kubeadm/init-config.yaml || true