Support adopting existing radosgw buckets and users

The operator previously assumed it created every user and bucket it managed:
reconciling an existing resource could overwrite its user attributes or wipe its
bucket policy, and deleting a CRD always deleted the underlying RGW object (only
Bucket had retainOnDelete). That made taking over pre-existing radosgw state
unsafe. Make adoption first-class.

- add retainOnDelete to ObjectStoreUser and BucketAccess (dedicated users), so
  deleting the CRD orphans the RGW user instead of deleting it (symmetric with
  Bucket)
- merge bucket policy instead of replacing it: the operator marks its own
  statements with a cephrgwop* Sid and preserves any statement it does not own,
  so adopting a bucket with a hand-written policy keeps it; add Bucket
  managePolicy (default true) to opt out of policy management entirely
- only reconcile user attributes the spec sets: DisplayName when non-empty and
  Suspended is now an optional *bool, so adopting a user does not reset them
- record adoption: ObjectStoreUser/Bucket status.adopted (+ printcolumn) is true
  when the RGW object already existed on first reconcile
- add GetBucketPolicy + MergeBucketPolicy; keyed adoption detection off the
  status identity field so a Pending owner wait does not mislabel it
- regenerate CRDs/deepcopy; add docs/adoption.md and
  config/samples/05-adoption.yaml; cover the merge in policy_test.go

Claude-Session: https://claude.ai/code/session_016CEncETbf8cvy1PhsHfFHM

internal/controller/objectstoreuser_controller.go

@@ -40,7 +40,9 @@ func (r *ObjectStoreUserReconciler) Reconcile(ctx context.Context, req ctrl.Requ
 
 	if !osu.DeletionTimestamp.IsZero() {
 		if controllerutil.ContainsFinalizer(&osu, finalizer) {
-			if err := r.Ceph.DeleteUser(ctx, uid); err != nil {
+			if osu.Spec.RetainOnDelete {
+				logger.Info("retaining RGW user on delete", "uid", uid)
+			} else if err := r.Ceph.DeleteUser(ctx, uid); err != nil {
 				return r.fail(ctx, &osu, "DeleteFailed", err)
 			}
 			controllerutil.RemoveFinalizer(&osu, finalizer)
@@ -65,17 +67,31 @@ func (r *ObjectStoreUserReconciler) Reconcile(ctx context.Context, req ctrl.Requ
 		Suspended:   osu.Spec.Suspended,
 	}
 
-	if _, err := r.Ceph.GetUser(ctx, uid); ceph.IsNotFound(err) {
+	// Record adoption once: whether the RGW user already existed the first time
+	// we reconciled this resource (taken over rather than created). status.UID is
+	// only set on a successful reconcile, so it is a clean "never provisioned"
+	// signal that transient failures do not pollute.
+	firstObserve := osu.Status.UID == ""
+	_, getErr := r.Ceph.GetUser(ctx, uid)
+	switch {
+	case ceph.IsNotFound(getErr):
 		if _, err := r.Ceph.CreateUser(ctx, spec); err != nil {
 			return r.fail(ctx, &osu, "CreateFailed", err)
 		}
 		logger.Info("created RGW user", "uid", uid)
-	} else if err != nil {
-		return r.fail(ctx, &osu, "LookupFailed", err)
-	} else {
+		if firstObserve {
+			osu.Status.Adopted = false
+		}
+	case getErr != nil:
+		return r.fail(ctx, &osu, "LookupFailed", getErr)
+	default:
 		if _, err := r.Ceph.UpdateUser(ctx, spec); err != nil {
 			return r.fail(ctx, &osu, "UpdateFailed", err)
 		}
+		if firstObserve {
+			osu.Status.Adopted = true
+			logger.Info("adopted existing RGW user", "uid", uid)
+		}
 	}
 
 	if q := osu.Spec.Quota; q != nil {