Reapply "Add missing admin action files and navigation links"

This reverts commit 4d515bc400.

src/app/admin/import/effects/page.tsx

@@ -0,0 +1,12 @@
+// src/app/[locale]/admin/import/effects/page.tsx
+import { redirect } from 'next/navigation'
+import { canAccess, getAdminContext, PERMS } from '@/lib/permissions'
+import { ImportEffectsClient } from './import-effects-client'
+
+export default async function ImportEffectsPage(_props: { params: Promise<{ locale: string }> }) {
+  const { session, permissions } = await getAdminContext()
+  if (!canAccess(permissions, PERMS.ASSETS_IMPORT, session.user.rank)) {
+    redirect('/admin')
+  }
+  return <ImportEffectsClient />
+}