Roll cephrgw-operator to v0.3.0 (safe adoption) (#279)

## Why

cephrgw-operator **v0.3.0** makes adopting pre-existing radosgw buckets/users safe (operator repo #5, merged): `retainOnDelete` on `ObjectStoreUser`/`BucketAccess`, non-destructive bucket-policy **merge** (+ `managePolicy`), non-destructive user attributes, and `status.adopted`.

## Changes

- bump the operator image `git.unkin.net/unkin/cephrgw-operator` → `v0.3.0`

No credential or manifest change beyond the tag. Validated with `kustomize build` on the au-syd1 overlay.

https://claude.ai/code/session_016CEncETbf8cvy1PhsHfFHM
Reviewed-on: #279
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>

apps/base/cephrgw-system/deployment.yaml

@@ -24,7 +24,7 @@ spec:
         runAsNonRoot: true
       containers:
         - name: operator
-          image: git.unkin.net/unkin/cephrgw-operator:v0.2.0
+          image: git.unkin.net/unkin/cephrgw-operator:v0.3.0
           args:
             - --metrics-bind-address=:8080
             - --health-probe-bind-address=:8081