Add OAuth flows and UI integration

- Implemented OAuth endpoints (providers list, authorization, callback, linked accounts management).
- Added UI translations for OAuth workflows (auth process messages, linked accounts management).
- Extended TypeScript types and React hooks to support OAuth features.
- Updated app configuration with OAuth-specific settings and provider details.
- Introduced skeleton implementations for authorization and token endpoints in provider mode.
- Included unit test and integration hooks for OAuth capabilities.

frontend/src/app/[locale]/(authenticated)/settings/accounts/page.tsx

@@ -0,0 +1,24 @@
+/**
+ * Linked Accounts Settings Page
+ * Manage linked OAuth provider accounts
+ */
+
+'use client';
+
+import { useTranslations } from 'next-intl';
+import { LinkedAccountsSettings } from '@/components/settings';
+
+export default function LinkedAccountsPage() {
+  const t = useTranslations('settings.linkedAccounts');
+
+  return (
+    <div className="space-y-6">
+      <div>
+        <h2 className="text-2xl font-semibold text-foreground">{t('pageTitle')}</h2>
+        <p className="text-muted-foreground mt-1">{t('pageSubtitle')}</p>
+      </div>
+
+      <LinkedAccountsSettings />
+    </div>
+  );
+}