Implement modern file manager with drag-and-drop interface

Major UI/UX improvements to replace clunky sidebar with modern grid layout:

- Add FileManagerModern component with grid-based file browser
- Implement drag-and-drop file upload with validation and progress
- Add comprehensive context menu with file operations (copy/cut/paste/delete)
- Create intelligent file selection system with multi-select support
- Add modern toolbar with search, view switching, and file operations
- Integrate seamless view switching between classic and modern interfaces
- Support keyboard shortcuts and accessibility features
- Add complete i18n support for all new interface elements

Technical components:
- FileManagerGrid: Grid layout with breadcrumb navigation
- FileManagerContextMenu: Right-click context menu system
- useFileSelection: Hook for managing file selection state
- useDragAndDrop: Hook for handling drag-and-drop operations
- View switching logic integrated into main FileManager component

The modern interface is now the default while maintaining backward compatibility.
Users can switch between modern and classic views seamlessly.

src/locales/zh/translation.json

@@ -642,6 +642,33 @@
     "folderCreatedSuccessfully": "文件夹 \"{{name}}\" 创建成功",
     "failedToCreateFolder": "创建文件夹失败",
     "itemDeletedSuccessfully": "{{type}}删除成功",
+    "itemsDeletedSuccessfully": "{{count}} 个项目删除成功",
+    "failedToDeleteItems": "删除项目失败",
+    "dragFilesToUpload": "拖拽文件到这里上传",
+    "emptyFolder": "此文件夹为空",
+    "itemCount": "{{count}} 个项目",
+    "selectedCount": "已选择 {{count}} 个",
+    "searchFiles": "搜索文件...",
+    "upload": "上传",
+    "selectHostToStart": "选择主机开始文件管理",
+    "failedToConnect": "连接SSH失败",
+    "failedToLoadDirectory": "加载目录失败",
+    "noSSHConnection": "无SSH连接可用",
+    "enterFolderName": "输入文件夹名称：",
+    "enterFileName": "输入文件名称：",
+    "copy": "复制",
+    "cut": "剪切",
+    "paste": "粘贴",
+    "delete": "删除",
+    "properties": "属性",
+    "preview": "预览",
+    "refresh": "刷新",
+    "downloadFiles": "下载 {{count}} 个文件",
+    "copyFiles": "复制 {{count}} 个项目",
+    "cutFiles": "剪切 {{count}} 个项目",
+    "deleteFiles": "删除 {{count}} 个项目",
+    "filesCopiedToClipboard": "{{count}} 个项目已复制到剪贴板",
+    "filesCutToClipboard": "{{count}} 个项目已剪切到剪贴板",
     "failedToDeleteItem": "删除项目失败",
     "itemRenamedSuccessfully": "{{type}}重命名成功",
     "failedToRenameItem": "重命名项目失败",