FEATURE: Comprehensive multimedia file handling with professional components

- Integrated react-markdown with GitHub Flavored Markdown support
- Added react-pdf for PDF viewing with full navigation controls
- Implemented react-syntax-highlighter for code syntax highlighting
- Added dual-pane Markdown editor with live preview capability
- Fixed PDF.js worker configuration with local fallback
- Enhanced internationalization support for all multimedia controls
- Removed unsupported download buttons from Markdown editor
- Resolved version compatibility issues between PDF API and worker

技术改进 Claude Code生成

Co-Authored-By: Claude <noreply@anthropic.com>

src/locales/zh/translation.json

@@ -691,6 +691,13 @@
     "connectToSsh": "连接 SSH 以使用文件操作",
     "uploadFile": "上传文件",
     "downloadFile": "下载",
+    "edit": "编辑",
+    "preview": "预览",
+    "previous": "上一页",
+    "next": "下一页",
+    "pageXOfY": "第 {{current}} 页，共 {{total}} 页",
+    "zoomOut": "缩小",
+    "zoomIn": "放大",
     "newFile": "新建文件",
     "newFolder": "新建文件夹",
     "rename": "重命名",