ci: add disposable Longhorn scratch storage for builds

infrastructure/core/kustomization.yaml

@@ -3,6 +3,7 @@ apiVersion: kustomize.config.k8s.io/v1beta1
 kind: Kustomization
 resources:
   - node-maintenance.yaml
+  - storageclass-ci-scratch.yaml
   - ../modules/base
   - ../modules/profiles/atlas-ha
   - node-prefer-noschedule-serviceaccount.yaml

infrastructure/core/storageclass-ci-scratch.yaml

@@ -0,0 +1,17 @@
+# infrastructure/core/storageclass-ci-scratch.yaml
+apiVersion: storage.k8s.io/v1
+kind: StorageClass
+metadata:
+  name: ci-scratch
+provisioner: driver.longhorn.io
+reclaimPolicy: Delete
+volumeBindingMode: Immediate
+allowVolumeExpansion: true
+parameters:
+  diskSelector: astreae
+  numberOfReplicas: "1"
+  staleReplicaTimeout: "30"
+  fsType: ext4
+  dataLocality: disabled
+# Reproducible build scratch only. Jenkins removes the PVC with its agent pod.
+# A lost scratch replica requires a fresh build, never an application restore.