fix: include BASE_PATH and ?local in OIDC post-logout redirect URI

Without BASE_PATH the redirect fails behind a reverse proxy. Adding
?local prevents the SSO auto-redirect from immediately signing the
user back in after logout.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/auth/auth-store.ts

@@ -1,5 +1,6 @@
 import { create } from 'zustand';
 import { api } from '../api/client';
+import { config } from '../config';
 
 interface AuthState {
   accessToken: string | null;
@@ -154,7 +155,7 @@ export const useAuthStore = create<AuthState>((set, get) => ({
       error: null,
     });
     if (endSessionEndpoint && idToken) {
-      const postLogoutRedirect = `${window.location.origin}/login`;
+      const postLogoutRedirect = `${window.location.origin}${config.basePath}login?local`;
       const params = new URLSearchParams({
         id_token_hint: idToken,
         post_logout_redirect_uri: postLogoutRedirect,