feat(creator-studio): switch writing editor to TinyMCE

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

assets/creator-studio/build/index.asset.php

@@ -1 +1 @@
-<?php return array('dependencies' => array('react', 'wp-api-fetch', 'wp-block-editor', 'wp-block-library', 'wp-blocks', 'wp-components', 'wp-compose', 'wp-data', 'wp-element', 'wp-hooks', 'wp-i18n', 'wp-wordcount'), 'version' => 'a7a69219755aa071c854');
+<?php return array('dependencies' => array('react', 'wp-element', 'wp-i18n'), 'version' => '7498c793a760249be02b');