Exposes the legacy mediafs CephFS filesystem to the arrstack namespace so the upcoming mediamover tool can migrate media and run bandwidth tests against the old filesystem; the ceph-mediafs client secret is already seeded in Vault. The mover deployment itself lands in a follow-up PR.
- Adds a `ceph-mediafs-secret` VaultStaticSecret in csi-cephfs syncing `kv/service/kubernetes/au/syd1/csi/ceph-mediafs-secret`
- Adds a 10Ti static RWX PV `arrstack-mediafs` (fsName `mediafs`, rootPath `/`, staged with the mediafs secret) pinned by claimRef
- Adds the matching `mediafs` PVC in arrstack (storageClassName "", volumeName-bound, backups excluded)
- Registers all three in their base kustomizations
Reviewed-on: #391
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>
