feat(creator-studio): icon toolbar with block tools, drop author strip

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

assets/creator-studio/scripts/preview.cjs

@@ -68,7 +68,6 @@ const mockBootstrap = {
     isLoggedIn: true,
   },
   limits: { titleMin: 5, titleMax: 100, titlePlaceholder: '请输入标题', contentPlaceholder: '请输入正文' },
-  author: { name: '预览作者', avatar: '', meta: '' },
   privateUploads: [],
   privateStorage: false,
   media: { maxBytes: 5242880, batch: 6 },