实现跨边界拖拽功能：支持从浏览器拖拽文件到系统

主要改进：
- 使用 File System Access API 实现真正的跨应用边界文件传输
- 支持拖拽到窗口外自动触发系统保存对话框
- 智能路径记忆功能，记住用户上次选择的保存位置
- 多文件自动打包为 ZIP 格式
- 现代浏览器优先使用新 API，旧浏览器降级到传统下载
- 完整的视觉反馈和进度显示

技术实现：
- 新增 useDragToSystemDesktop hook 处理系统级拖拽
- 扩展 Electron 主进程支持拖拽临时文件管理
- 集成 JSZip 库支持多文件打包
- 使用 IndexedDB 存储用户偏好的保存路径
- 优化文件管理器拖拽事件处理链

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

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

electron/main.cjs

@@ -1,6 +1,7 @@
-const { app, BrowserWindow, shell, ipcMain } = require("electron");
+const { app, BrowserWindow, shell, ipcMain, dialog } = require("electron");
 const path = require("path");
 const fs = require("fs");
+const os = require("os");
 
 let mainWindow = null;
 
@@ -317,8 +318,185 @@ app.on("activate", () => {
   }
 });
 
+// ================== 拖拽功能实现 ==================
+
+// 临时文件管理
+const tempFiles = new Map(); // 存储临时文件路径映射
+
+// 创建临时文件
+ipcMain.handle("create-temp-file", async (event, fileData) => {
+  try {
+    const { fileName, content, encoding = 'base64' } = fileData;
+
+    // 创建临时目录
+    const tempDir = path.join(os.tmpdir(), 'termix-drag-files');
+    if (!fs.existsSync(tempDir)) {
+      fs.mkdirSync(tempDir, { recursive: true });
+    }
+
+    // 生成临时文件路径
+    const tempId = Date.now() + '-' + Math.random().toString(36).substr(2, 9);
+    const tempFilePath = path.join(tempDir, `${tempId}-${fileName}`);
+
+    // 写入文件内容
+    if (encoding === 'base64') {
+      const buffer = Buffer.from(content, 'base64');
+      fs.writeFileSync(tempFilePath, buffer);
+    } else {
+      fs.writeFileSync(tempFilePath, content, 'utf8');
+    }
+
+    // 记录临时文件
+    tempFiles.set(tempId, {
+      path: tempFilePath,
+      fileName: fileName,
+      createdAt: Date.now()
+    });
+
+    console.log(`Created temp file: ${tempFilePath}`);
+    return { success: true, tempId, path: tempFilePath };
+  } catch (error) {
+    console.error("Error creating temp file:", error);
+    return { success: false, error: error.message };
+  }
+});
+
+// 开始拖拽到桌面
+ipcMain.handle("start-drag-to-desktop", async (event, { tempId, fileName }) => {
+  try {
+    const tempFile = tempFiles.get(tempId);
+    if (!tempFile) {
+      throw new Error("Temporary file not found");
+    }
+
+    // 使用Electron的startDrag API
+    const iconPath = path.join(__dirname, "..", "public", "icon.png");
+    const iconExists = fs.existsSync(iconPath);
+
+    mainWindow.webContents.startDrag({
+      file: tempFile.path,
+      icon: iconExists ? iconPath : undefined
+    });
+
+    console.log(`Started drag for: ${tempFile.path}`);
+    return { success: true };
+  } catch (error) {
+    console.error("Error starting drag:", error);
+    return { success: false, error: error.message };
+  }
+});
+
+// 清理临时文件
+ipcMain.handle("cleanup-temp-file", async (event, tempId) => {
+  try {
+    const tempFile = tempFiles.get(tempId);
+    if (tempFile && fs.existsSync(tempFile.path)) {
+      fs.unlinkSync(tempFile.path);
+      tempFiles.delete(tempId);
+      console.log(`Cleaned up temp file: ${tempFile.path}`);
+    }
+    return { success: true };
+  } catch (error) {
+    console.error("Error cleaning up temp file:", error);
+    return { success: false, error: error.message };
+  }
+});
+
+// 批量清理过期临时文件（5分钟过期）
+const cleanupExpiredTempFiles = () => {
+  const now = Date.now();
+  const maxAge = 5 * 60 * 1000; // 5分钟
+
+  for (const [tempId, tempFile] of tempFiles.entries()) {
+    if (now - tempFile.createdAt > maxAge) {
+      try {
+        if (fs.existsSync(tempFile.path)) {
+          fs.unlinkSync(tempFile.path);
+        }
+        tempFiles.delete(tempId);
+        console.log(`Auto-cleaned expired temp file: ${tempFile.path}`);
+      } catch (error) {
+        console.error("Error auto-cleaning temp file:", error);
+      }
+    }
+  }
+};
+
+// 每分钟清理一次过期临时文件
+setInterval(cleanupExpiredTempFiles, 60 * 1000);
+
+// 创建临时文件夹拖拽支持
+ipcMain.handle("create-temp-folder", async (event, folderData) => {
+  try {
+    const { folderName, files } = folderData;
+
+    // 创建临时目录
+    const tempDir = path.join(os.tmpdir(), 'termix-drag-folders');
+    if (!fs.existsSync(tempDir)) {
+      fs.mkdirSync(tempDir, { recursive: true });
+    }
+
+    const tempId = Date.now() + '-' + Math.random().toString(36).substr(2, 9);
+    const tempFolderPath = path.join(tempDir, `${tempId}-${folderName}`);
+
+    // 递归创建文件夹结构
+    const createFolderStructure = (basePath, fileList) => {
+      for (const file of fileList) {
+        const fullPath = path.join(basePath, file.relativePath);
+        const dirPath = path.dirname(fullPath);
+
+        // 确保目录存在
+        if (!fs.existsSync(dirPath)) {
+          fs.mkdirSync(dirPath, { recursive: true });
+        }
+
+        // 写入文件
+        if (file.encoding === 'base64') {
+          const buffer = Buffer.from(file.content, 'base64');
+          fs.writeFileSync(fullPath, buffer);
+        } else {
+          fs.writeFileSync(fullPath, file.content, 'utf8');
+        }
+      }
+    };
+
+    fs.mkdirSync(tempFolderPath, { recursive: true });
+    createFolderStructure(tempFolderPath, files);
+
+    // 记录临时文件夹
+    tempFiles.set(tempId, {
+      path: tempFolderPath,
+      fileName: folderName,
+      createdAt: Date.now(),
+      isFolder: true
+    });
+
+    console.log(`Created temp folder: ${tempFolderPath}`);
+    return { success: true, tempId, path: tempFolderPath };
+  } catch (error) {
+    console.error("Error creating temp folder:", error);
+    return { success: false, error: error.message };
+  }
+});
+
 app.on("before-quit", () => {
   console.log("App is quitting...");
+
+  // 清理所有临时文件
+  for (const [tempId, tempFile] of tempFiles.entries()) {
+    try {
+      if (fs.existsSync(tempFile.path)) {
+        if (tempFile.isFolder) {
+          fs.rmSync(tempFile.path, { recursive: true, force: true });
+        } else {
+          fs.unlinkSync(tempFile.path);
+        }
+      }
+    } catch (error) {
+      console.error("Error cleaning up temp file on quit:", error);
+    }
+  }
+  tempFiles.clear();
 });
 
 app.on("will-quit", () => {