Declare ext-intl and ext-zip as explicit composer requirements

DataExportService uses ZipArchive directly and the Dutch-locale
format_datetime Twig filter needs real ext-intl (the polyfill only
supports en), but composer.json only declared ext-ctype/ext-iconv.
Adding them lets `composer check-platform-reqs` catch a missing
extension before a runtime crash.

composer.json

@@ -9,6 +9,8 @@
         "php": ">=8.5",
         "ext-ctype": "*",
         "ext-iconv": "*",
+        "ext-intl": "*",
+        "ext-zip": "*",
         "doctrine/dbal": "^4.4.3",
         "doctrine/doctrine-bundle": "^3.2.2",
         "doctrine/doctrine-migrations-bundle": "^4.0",