Implement autobackup-operator controllers, tests, CI and packaging

PVCs and CloudNativePG Clusters need S3 buckets and backup schedules
provisioned consistently. This operator watches the
backups.unkin.net/{schedule,destination} annotations on those objects and
provisions everything needed to back them up, with no new CRDs.

- Add a PVC controller that provisions cephrgw ObjectStoreUser/Bucket/BucketAccess,
  auto-generates a restic repo-password Secret and creates a k8up Schedule scoped
  to the PVC via spec.backup.volumes[].persistentVolumeClaim.claimName.
- Add a CNPG Cluster controller that provisions the same bucket stack, idempotently
  patches spec.backup.barmanObjectStore (leaving a user-set destinationPath alone
  with a Warning event) and creates a ScheduledBackup.
- Resolve destinations through a ConfigMap lookup table; requeue until the
  BucketAccess is Ready before creating schedule resources; own-reference created
  resources and retain bucket data by default.
- Add schedule-mapping helpers (k8up 5-field/shortcut pass-through, CNPG 6-field
  seconds-first) and deterministic, length-bounded name derivation.
- Add unit tests (schedule mapping, name derivation, destination resolution) and
  envtest controller tests for both paths, wiring the external CRDs into envtest.
- Add kubebuilder-generated RBAC, a Dockerfile (distroless/nonroot), Woodpecker
  lint/test/build pipelines and a tag-triggered image push to the artifactapi
  docker-internal registry, plus a version-bump Makefile and deploy manifests.

test/crds/postgresql.cnpg.io_clusters.yaml

@@ -0,0 +1,31 @@
+# Minimal CloudNativePG Cluster CRD for envtest. The real CNPG CRD is installed
+# at runtime; here spec/status are open objects so we can create a Cluster and
+# assert the barmanObjectStore patch.
+apiVersion: apiextensions.k8s.io/v1
+kind: CustomResourceDefinition
+metadata:
+  name: clusters.postgresql.cnpg.io
+spec:
+  group: postgresql.cnpg.io
+  names:
+    kind: Cluster
+    listKind: ClusterList
+    plural: clusters
+    singular: cluster
+  scope: Namespaced
+  versions:
+    - name: v1
+      served: true
+      storage: true
+      subresources:
+        status: {}
+      schema:
+        openAPIV3Schema:
+          type: object
+          properties:
+            spec:
+              type: object
+              x-kubernetes-preserve-unknown-fields: true
+            status:
+              type: object
+              x-kubernetes-preserve-unknown-fields: true