Revert "Add missing admin action files and navigation links"

This reverts commit 41be6835bf.

src/app/admin/translations/page.tsx

@@ -1,7 +0,0 @@
-import { redirect } from 'next/navigation'
-
-// Default landing for /admin/translations → first tab.
-// The shared TranslationsTabs (in layout.tsx) gives access to every section.
-export default function TranslationsHubPage() {
-  redirect('/admin/translations/cms')
-}