修复: PDF导出浏览器探测补全与链路加固

- 浏览器探测补按用户安装路径LOCALAPPDATA
- fs-agent远程HTML导出先拉取到本地临时目录
- Markdown通道空结果守卫,杜绝0字节PDF误报成功
- 清理死参数与无调用死代码

internal/api/pdf_api.go

@@ -73,7 +73,7 @@ func (api *PdfAPI) ExportMarkdownToPDF(req PdfExportRequest) (*PdfExportResponse
 	htmlContent := api.markdownToHTML(req.Content, req.Title, req.FontSize)
 
 	// 使用chromedp生成PDF
-	pdfBuffer, err := api.generatePDFFromHTML(htmlContent, req.Title, req.PageWidth, req.PageHeight)
+	pdfBuffer, err := api.generatePDFFromHTML(htmlContent, req.PageWidth, req.PageHeight)
 	if err != nil {
 		return nil, fmt.Errorf("生成PDF失败: %v", err)
 	}
@@ -264,7 +264,7 @@ func (api *PdfAPI) markdownToHTML(markdownContent string, title string, fontSize
 }
 
 // generatePDFFromHTML 使用chromedp从HTML生成PDF
-func (api *PdfAPI) generatePDFFromHTML(htmlContent, title string, pageWidth, pageHeight int) ([]byte, error) {
+func (api *PdfAPI) generatePDFFromHTML(htmlContent string, pageWidth, pageHeight int) ([]byte, error) {
 	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
 	defer cancel()
 	// 配置chromedp选项
@@ -338,6 +338,10 @@ func (api *PdfAPI) generatePDFFromHTML(htmlContent, title string, pageWidth, pag
 		return nil, fmt.Errorf("chromedp执行失败: %v", err)
 	}
 
+	if len(buf) == 0 {
+		return nil, fmt.Errorf("PDF生成结果为空")
+	}
+
 	return buf, nil
 }
 
@@ -350,6 +354,8 @@ func findChromeExecutable() (string, error) {
 			filepath.Join(os.Getenv("USERPROFILE"), "AppData", "Local", "Google", "Chrome", "Application", "chrome.exe"),
 			`C:\Program Files (x86)\Microsoft\Edge\Application\msedge.exe`,
 			`C:\Program Files\Microsoft\Edge\Application\msedge.exe`,
+			// 按用户安装的 Edge 不落在 Program Files，LOCALAPPDATA 下才有
+			filepath.Join(os.Getenv("LOCALAPPDATA"), "Microsoft", "Edge", "Application", "msedge.exe"),
 		}
 		for _, path := range candidates {
 			if _, err := os.Stat(path); err == nil {
@@ -520,14 +526,4 @@ func (api *PdfAPI) getDesktopDirectory() string {
 	
 	// 备用：当前目录
 	return "."
-}
-
-// SelectDirectory 选择保存目录（简化版，实际应该使用Wails runtime）
-func (api *PdfAPI) SelectDirectory() (string, error) {
-	// 简化版：直接返回桌面目录
-	desktop := api.getDesktopDirectory()
-	if desktop == "." {
-		return "", fmt.Errorf("无法确定默认目录")
-	}
-	return desktop, nil
 }