Keep wordpress-importer.zip for older versions of Playground (#2647)

Author: brandonpayton

packages/playground/website-deployment/custom-redirects-lib.php

@@ -345,6 +345,7 @@ function playground_get_custom_response_headers( $requested_path ) {
 				'logger.php',
 				'oauth.php',
 				'wp-cli.phar',
+				'wordpress-importer.zip',
 			),
 			true
 		)

packages/playground/website/.htaccess

@@ -5,7 +5,7 @@ AddEncoding x-gzip .gz
 Header unset ETag
 Header set Cache-Control "max-age=0, no-cache, no-store, must-revalidate"
 </FilesMatch>
-<FilesMatch "index\.js|blueprint-schema\.json|logger.php|wp-cli.phar">
+<FilesMatch "index\.js|blueprint-schema\.json|logger.php|wp-cli.phar|wordpress-importer.zip">
 Header set Access-Control-Allow-Origin "*"
 Header unset ETag
 Header set Cache-Control "max-age=0, no-cache, no-store, must-revalidate"

packages/playground/website/public/wordpress-importer.zip

@@ -0,0 +1,12 @@
+# Why we are keeping this file
+
+As of today (2025-09-18), the latest version WordPress Playground is using
+the WP core version of the WordPress Importer plugin and no longer needs
+the Humanmade fork we were using and hosting at
+https://playground.wordpress.net/wordpress-importer.zip.
+However, there are older versions of Playground out there, including self-hosted
+instances that still depend on that importer URL.
+
+Let's keep serving the last-used version of that wordpress-importer.zip
+for such users until we are able make self-hosted instances truly independent
+of playground.wordpress.net resources.