fix: 修复下载功能，通过background script直接下载到默认目录

- 下载改由background script处理，使用chrome.downloads.download API
- 添加chrome.runtime.sendMessage类型定义
- 修复SVG图标路径错误
- 使用Data URL方式确保下载可靠性

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

src/background/index.ts

@@ -1,34 +1,31 @@
 // Background Service Worker
 // 处理下载等后台任务
 
-import type { ExtractedContent } from '../types';
-import { generateMarkdown } from '../utils/markdown';
-import { downloadMarkdown, generateFilename } from '../utils/download';
-
 // 监听来自popup的消息
 chrome.runtime.onMessage.addListener((message: any, _sender: any, sendResponse: (response?: any) => void) => {
   if (message.action === 'download') {
-    handleDownload(message.data)
+    handleDownload(message.filename, message.content)
       .then(() => sendResponse({ success: true }))
       .catch(error => sendResponse({ success: false, error: error?.message || 'Download failed' }));
     return true; // 异步响应
   }
 
-  if (message.action === 'copy') {
-    sendResponse({ success: false, error: 'Copy should be handled in popup' });
-    return false;
-  }
-
   return false;
 });
 
-// 处理下载
-async function handleDownload(data: { content: ExtractedContent; options: { includeTitle: boolean; includeUrl: boolean } }): Promise<void> {
-  const { content, options } = data;
-  const markdown = generateMarkdown(content, options);
-  const filename = generateFilename(content.title);
+// 处理下载 - 直接下载到默认目录
+async function handleDownload(filename: string, content: string): Promise<void> {
+  // 使用 Data URL 方式（更可靠）
+  const dataUrl = `data:text/markdown;charset=utf-8,${encodeURIComponent(content)}`;
 
-  await downloadMarkdown(markdown, filename);
+  // 使用 chrome.downloads.download 直接下载到默认目录
+  const downloadId = await chrome.downloads.download({
+    url: dataUrl,
+    filename: filename,
+    saveAs: false  // 直接保存到默认下载目录
+  });
+
+  console.log('ReadMD: Download initiated', downloadId, filename);
 }
 
 // 下载完成后清理

src/popup/Popup.tsx

@@ -76,7 +76,7 @@ export function Popup() {
     }
   };
 
-  // 下载文件
+  // 下载文件 - 通过 background script 直接下载到默认目录
   const handleDownload = async () => {
     if (!extractedContent) return;
 
@@ -86,16 +86,15 @@ export function Popup() {
         includeUrl: settings.includeUrl
       });
 
-      const blob = new Blob([markdown], { type: 'text/markdown;charset=utf-8' });
-      const url = URL.createObjectURL(blob);
       const filename = `${extractedContent.title.replace(/[<>:"/\\|?*]/g, '_').substring(0, 100)}.md`;
-      await chrome.downloads.download({
-        url: url,
+
+      // 发送消息给 background script 处理下载
+      await chrome.runtime.sendMessage({
+        action: 'download',
         filename: filename,
-        saveAs: false
+        content: markdown
       });
 
-      URL.revokeObjectURL(url);
       showStatus('success', '开始下载...');
       setTimeout(() => {
         window.close();
@@ -200,7 +199,7 @@ export function Popup() {
         >
           <svg className="w-4 h-4" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
             <circle cx="12" cy="12" r="3"/>
-            <path d="M19.4 15a1.65 1.65 0 0 0 .33 1.82l.06.06a2 2 0 0 2.0 1 83 2 2 0 0 1-2.83 0l-.06-.06a1.65 1.65 0 0 0-1.82-.33 1.65 1.65 0 0 0-1 1.51V21a2 2 0 0 1-2 2 2 2 0 0 1-2-2v-.09A1.65 1.65 0 0 0 9 19.4a1.65 1.65 0 0 0-1.82.33l-.06.06a2 2 0 0 1-2.83 0 2 2 0 0 1 0-2.83l.06-.06a1.65 1.65 0 0 0 .33-1.82 1.65 1.65 0 0 0-1.51-1H3a2 2 0 0 1-2-2 2 2 0 0 1 2-2h.09A1.65 1.65 0 0 0 4.6 9a1.65 1.65 0 0 0-.33-1.82l-.06-.06a2 2 0 0 1 0-2.83 2 2 0 0 1 2.83 0l.06.06a1.65 1.65 0 0 0 1.82.33H9a1.65 1.65 0 0 0 1-1.51V3a2 2 0 0 1 2-2 2 2 0 0 1 2 2v.09a1.65 1.65 0 0 0 1 1.51 1.65 1.65 0 0 0 1.82-.33l.06-.06a2 2 0 0 1 2.83 0 2 2 0 0 1 0 2.83l-.06.06a1.65 1.65 0 0 0-.33 1.82V9a1.65 1.65 0 0 0 1.51 1H21a2 2 0 0 1 2 2 2 2 0 0 1-2 2h-.09a1.65 1.65 0 0 0-1.51 1z"/>
+            <path d="M12.36 6v1.2M12.36 16.8v1.2M6.36 12H5.16M18.84 12h-1.2M8.4 8.4l-.85.85M16.45 15.55l-.85.85M8.4 15.6l-.85-.85M16.45 8.45l-.85-.85"/>
           </svg>
           设置
         </button>

src/types/chrome.d.ts

@@ -8,6 +8,7 @@ declare const chrome: {
     onMessage: {
       addListener: (callback: (message: any, sender: any, sendResponse: (response?: any) => void) => boolean | void) => void;
     };
+    sendMessage: (message: any) => Promise<any>;
     openOptionsPage: () => Promise<void>;
   };
   downloads: {