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

app_pdf.go

@@ -76,13 +76,3 @@ func (a *App) ExportHtmlFileToPDF(path string, saveName string) (map[string]inte
 		"size":    result.Size,
 	}, nil
 }
-
-// SelectPDFSaveDirectory 选择PDF保存目录
-func (a *App) SelectPDFSaveDirectory() (string, error) {
-	pdfAPI, err := a.requirePdfAPI()
-	if err != nil {
-		return "", err
-	}
-
-	return pdfAPI.SelectDirectory()
-}