feat(media): default to s3 with local upload fallback

apps/admin/src/app/media/page.tsx

@@ -81,7 +81,8 @@ export default async function MediaManagementPage({
         <h2 className="text-xl font-medium">Upload Media Asset</h2>
         <p className="mt-1 text-sm text-neutral-600">
           Upload storage provider: <strong>{activeStorageProvider}</strong>. You can switch via
-          `CMS_MEDIA_STORAGE_PROVIDER` (`local` or `s3`) until the admin settings toggle lands.
+          `CMS_MEDIA_STORAGE_PROVIDER` (`s3` default, `local` fallback) until the admin settings
+          toggle lands.
         </p>
         <MediaUploadForm />
       </section>