Refactor app instance to Keycloak SSO

app-instance/frontend/app/(auth)/login/page.tsx

@@ -3,23 +3,45 @@
 import { useEffect } from 'react';
 import { useSearchParams } from 'next/navigation';
 
-import { buildAuthPortalUrl } from '@/lib/auth-portal';
+import { startKeycloakLogin } from '@/lib/keycloak-oidc';
 import { pickAppText } from '@/lib/i18n/core';
 import { useAppI18n } from '@/lib/i18n/provider';
 
 export default function LoginRedirectPage() {
   const { locale } = useAppI18n();
   const searchParams = useSearchParams();
+  const loggedOut = searchParams?.get('logged_out') === '1';
 
   useEffect(() => {
+    if (loggedOut) return;
     const nextPath = searchParams?.get('next') || '/';
-    window.location.replace(buildAuthPortalUrl('/login', nextPath));
-  }, [searchParams]);
+    void startKeycloakLogin(nextPath);
+  }, [loggedOut, searchParams]);
+
+  if (loggedOut) {
+    return (
+      <div className="flex min-h-screen flex-col items-center justify-center gap-4 px-4 text-center">
+        <div className="text-sm text-muted-foreground">
+          {pickAppText(locale, '你已退出登录。', 'You have signed out.')}
+        </div>
+        <button
+          type="button"
+          className="rounded-full bg-primary px-5 py-2 text-sm font-semibold text-primary-foreground"
+          onClick={() => {
+            const nextPath = searchParams?.get('next') || '/';
+            void startKeycloakLogin(nextPath);
+          }}
+        >
+          {pickAppText(locale, '重新登录', 'Sign in again')}
+        </button>
+      </div>
+    );
+  }
 
   return (
     <div className="flex min-h-screen items-center justify-center px-4">
       <div className="text-sm text-muted-foreground">
-        {pickAppText(locale, '正在跳转到登录门户...', 'Redirecting to the sign-in portal...')}
+        {pickAppText(locale, '正在跳转到 Keycloak 登录...', 'Redirecting to Keycloak sign-in...')}
       </div>
     </div>
   );