优化文件管理器拖拽体验：实现智能跟随tooltip和统一状态管理

- 统一拖拽状态管理：将分散的draggedFiles、dragOverTarget、isDragging等状态合并为单一DragState
- 实现跟随鼠标的动态tooltip：实时显示拖拽操作提示，根据目标文件类型智能变化
- 支持三种拖拽模式：
  * 拖拽到文件夹显示"移动到xxx"
  * 拖拽到文件显示"与xxx进行diff对比"
  * 拖拽到空白区域显示"拖到窗口外下载"
- 修复边界情况：文件拖拽到自身时忽略操作，避免错误触发
- 使用shadcn设计token统一样式风格
- 移除冗余的DragIndicator组件，简化UI界面
- 添加全局鼠标移动监听，确保tooltip平滑跟随

🤖 Generated with [Claude Code](https://claude.ai/code)

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

src/ui/Desktop/Apps/File Manager/FileManagerModern.tsx

@@ -8,7 +8,6 @@ import { FileWindow } from "./components/FileWindow";
 import { DiffWindow } from "./components/DiffWindow";
 import { useDragToDesktop } from "../../../hooks/useDragToDesktop";
 import { useDragToSystemDesktop } from "../../../hooks/useDragToSystemDesktop";
-import { DragIndicator } from "../../../components/DragIndicator";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import { toast } from "sonner";
@@ -1275,6 +1274,7 @@ function FileManagerContent({ initialHost, onClose }: FileManagerModernProps) {
           onPathChange={setCurrentPath}
           onRefresh={() => loadDirectory(currentPath)}
           onUpload={handleFilesDropped}
+          onDownload={(files) => files.forEach(handleDownloadFile)}
           onContextMenu={handleContextMenu}
           viewMode={viewMode}
           onRename={handleRenameConfirm}
@@ -1322,29 +1322,6 @@ function FileManagerContent({ initialHost, onClose }: FileManagerModernProps) {
           onDragToDesktop={() => handleDragToDesktop(contextMenu.files)}
         />
 
-        {/* 拖拽到桌面指示器 */}
-        <DragIndicator
-          isVisible={
-            dragToDesktop.isDownloading ||
-            dragToDesktop.isDragging ||
-            systemDrag.isDownloading ||
-            systemDrag.isDragging
-          }
-          isDragging={
-            systemDrag.isDragging || dragToDesktop.isDragging
-          }
-          isDownloading={
-            systemDrag.isDownloading || dragToDesktop.isDownloading
-          }
-          progress={
-            systemDrag.isDownloading || systemDrag.isDragging
-              ? systemDrag.progress
-              : dragToDesktop.progress
-          }
-          fileName={selectedFiles.length === 1 ? selectedFiles[0]?.name : undefined}
-          fileCount={selectedFiles.length}
-          error={systemDrag.error || dragToDesktop.error}
-        />
       </div>
     </div>
   );