Add settings endpoints and registration status check: implement new API endpoints for settings management, including registration status retrieval, and update the registration command handler to enforce registration rules based on site settings.

frontend/src/features/auth/api.ts

@@ -1,7 +1,12 @@
 import { apiRequest, setAccessToken } from '@/shared/api/client'
-import type { AuthResponse, CurrentUser } from '@/shared/api/types'
+import type { AuthResponse, CurrentUser, RegistrationStatus } from '@/shared/api/types'
 import { useAuthStore } from './store'
 
+/** Публично: включена ли открытая регистрация (для страниц входа/регистрации). */
+export function fetchRegistrationStatus() {
+  return apiRequest<RegistrationStatus>('/auth/registration')
+}
+
 export function login(userName: string, password: string) {
   return apiRequest<AuthResponse>('/auth/login', { method: 'POST', body: { userName, password } })
 }