fix(k3s): disable local-storage so Longhorn is the sole default StorageClass

The deployed cluster has TWO default StorageClasses — k3s's built-in local-path
AND longhorn — which is ambiguous for PVCs without an explicit class. Longhorn
(ADR-0003) is the cluster storage, so add local-storage to k3s --disable. Effective
on fresh installs (the k3s install task is idempotent → no restart of the running
cluster); the running dev cluster keeps both defaults harmlessly (all platform PVCs
pin storageClassName: longhorn). Rebuilds get a single default.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

infra/ansible/roles/k3s_server/defaults/main.yml

@@ -11,7 +11,11 @@ k3s_install_script: "/usr/local/bin/k3s-install.sh"
 # Components disabled at install so Cilium + Gateway API own networking (ADR-0001/0002).
 # flannel + kube-proxy + network-policy are disabled via dedicated flags below;
 # traefik + servicelb via --disable.
-k3s_disable: "traefik,servicelb"
+# local-storage: k3s ships local-path as a DEFAULT StorageClass, which collides with Longhorn's
+# default (two default SCs = ambiguous PVC binding). Longhorn (ADR-0003) is the cluster's storage,
+# so disable k3s local-path entirely → `longhorn` is the sole default. (Effective on fresh installs;
+# the k3s install task is idempotent, so this does not restart an existing cluster — see DECISIONS-LOG.)
+k3s_disable: "traefik,servicelb,local-storage"
 
 # Set per-play: 'primary' (runs --cluster-init) or 'secondary' (joins the primary).
 k3s_server_mode: "secondary"