refactor: adapt org-namespace lookup to principal name rename

Tracks the gpustack identity-consolidation effort: the unified
``principals`` table's URL-safe identifier column was renamed
``slug`` → ``name`` (with the legacy display ``name`` → ``display_name``).
The enterprise plugin's persisted org caches (``organizationList``,
``allOrganizations`` in localStorage) now write ``name`` instead of
``slug`` on each Organization row.

``getCurrentOrgNamespace`` reads those caches to compose the k8s
namespace (``gpustack-{name}``) for GPU-instance / storage CRDs.
Updated to read ``item.name`` so namespace resolution stays in sync
with what the enterprise plugin writes — otherwise every gpu-service
write would fall through to ``gpustack-default`` even when the user
has an Org context.

Stale ``slug`` references in surrounding comments also retitled to
``name`` to avoid divergence between code and prose. The namespace
format itself (``gpustack-{...}``) is unchanged — only the column it
sources is.

src/pages/cluster-management/config/types.ts

@@ -89,7 +89,7 @@ export interface ClusterListItem {
   worker_pools: NodePoolListItem[];
   k8s_volume_mounts?: VolumeMount[];
   // Backend ClusterPublic carries this; admin-"All" namespace
-  // resolution falls back to the cluster's owner Org slug.
+  // resolution falls back to the cluster's owner Org name.
   owner_principal_id?: number;
 }