feat: tease enterprise multi-tenancy and API key controls in OSS

Add an Organizations menu entry (admin-only) that routes to an upsell
page explaining the multi-tenancy module, and surface disabled
IP Access Control / Quota Limit items in the API Key dropdown with a
tooltip pointing at the enterprise edition. Both placeholders are
shadowed by the enterprise plugin at build time: the route merger
removes the OSS Organizations entry by name, and the dropdown skips
each placeholder when the same key is contributed via configActions.

src/locales/zh-CN/organizations.ts

@@ -0,0 +1,12 @@
+export default {
+  'organizations.upsell.title': '组织是企业版功能',
+  'organizations.upsell.subtitle':
+    '多租户可在团队间隔离用户、资源与配额。升级到 GPUStack 企业版即可管理组织。',
+  'organizations.upsell.featuresTitle': '企业版包含的能力',
+  'organizations.upsell.feature.orgs': '创建组织来分组用户并隔离工作负载',
+  'organizations.upsell.feature.members': '为每个组织管理成员与角色',
+  'organizations.upsell.feature.quotas': '为每个组织设置资源与 Token 配额',
+  'organizations.upsell.feature.isolation':
+    '按组织隔离 API 密钥、模型部署与资源',
+  'organizations.upsell.cta': '了解企业版'
+};