fix(creator-studio): 加载正文编辑格式工具栏

选中文字时的 RichText 加粗、斜体、链接等工具由 WordPress format-library 注册。
BlockTools 虽然提供 inline toolbar slot，但此前前台没有加载 wp-format-library，
因此正文选区没有格式工具。为 Creator Studio 前台显式加载该 script/style handle，
并将行内格式工具栏统一为深色圆角悬浮样式。

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' => '635f07e202f61f4e377f');
+<?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');