feat(items): add server field and improve item management

refactor(ai): enhance item structure generation with schema validation
feat(ai): add token usage tracking and cost calculation
fix(ui): improve item card number formatting with locale support
docs(items): add documentation for item value separation
test(items): add tests for value field validation

components/admin/items/AdminItemCreateView.tsx

@@ -32,6 +32,7 @@ export function AdminItemCreateView({ locale, categories, serverOptions }: Admin
         tags: payload.tags,
         metadata: payload.metadata,
         fields: payload.fields,
+        server: payload.server ?? null,
       };
 
       const response = await fetch("/api/admin/items", {