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/ru-RU/common.ts

@@ -46,6 +46,7 @@ export default {
   'common.button.enabled': 'Активно',
   'common.button.disabled': 'Отключено',
   'common.button.upgrade': 'Обновить',
+  'common.enterprise.feature': 'Available in GPUStack Enterprise',
   'common.input.holder': 'Введите значение',
   'common.validate.value': 'Поле {name} обязательно',
   'common.button.edit': 'Редактировать',