refactor: remove LocaleSwitcher component and update locale handling

- Removed LocaleSwitcher from NavUser, SiteHeader, and WorkbenchHeader components.
- Updated tests to reflect the removal of LocaleSwitcher.
- Changed default locale from "en-US" to "zh-CN" in i18n configuration.
- Refactored locale resolution logic to read configured locale without relying on browser language detection.
- Updated AgentDesk SDK to support language configuration from public API.
- Cleaned up unused auth options fetching in the auth API.

web/lib/api/auth.ts

@@ -6,17 +6,6 @@ export type LoginRequest = {
   password: string
 }
 
-export type AuthOptions = {
-  wxworkEnabled: boolean
-  oidcEnabled: boolean
-}
-
-export async function fetchAuthOptions() {
-  return request<AuthOptions>("/api/auth/options", {
-    skipAuth: true,
-  })
-}
-
 export async function loginWithPassword(payload: LoginRequest) {
   const data = await request<AuthSession>("/api/auth/login", {
     method: "POST",