feat: add a billing holder page

src/locales/ru-RU/billing.ts

@@ -0,0 +1,15 @@
+export default {
+  'billing.upsell.title': 'Billing is an Enterprise feature',
+  'billing.upsell.subtitle':
+    'Track spend, generate invoices, and enforce budgets across teams. Upgrade to GPUStack Enterprise to manage billing.',
+  'billing.upsell.featuresTitle': 'What you get in Enterprise',
+  'billing.upsell.feature.usage':
+    'See cost breakdowns by organization, user, and model',
+  'billing.upsell.feature.invoices':
+    'Generate invoices and export billing reports',
+  'billing.upsell.feature.budgets':
+    'Set budgets and spending limits with alerts',
+  'billing.upsell.feature.chargeback':
+    'Attribute and charge back usage to teams and projects',
+  'billing.upsell.cta': 'Learn about Enterprise'
+};

src/locales/ru-RU/menu.ts

@@ -29,6 +29,7 @@ export default {
   'menu.usage.usage': 'Использование',
   'menu.billingAndUsage': 'Использование и биллинг',
   'menu.billingAndUsage.usage': 'Использование',
+  'menu.billingAndUsage.billing': 'Биллинг',
   'menu.404': 'Ошибка 404',
   'menu.resources.workers': 'Воркеры',
   'menu.resources.gpus': 'GPUs',