fix: 更新图片下载功能以支持动态文件扩展名，并修复文件路径生成逻辑

service/xibao/image_gen.go

@@ -8,7 +8,6 @@ import (
 	"git.lxtend.com/qqbot/message"
 	"git.lxtend.com/qqbot/util"
 	"github.com/fogleman/gg"
-	"github.com/google/uuid"
 	"golang.org/x/image/font/opentype"
 )
 
@@ -29,10 +28,8 @@ func GenerateCongratulationImage(text string, inputFile, outputFile string, isGo
 	dc.DrawImage(im, 0, 0)
 	// 判断是否为图片
 	if imgUrl, ok := isImageCQ(text); ok {
-		fileName := uuid.New().String() + ".jpg"
-		filePath := "./tmp/" + fileName
-
-		if err := util.DownloadFile(imgUrl, filePath); err != nil {
+		filePath, err := util.DownloadFile(imgUrl, "/tmp")
+		if err != nil {
 			log.Print("无法下载图片:", err)
 			return
 		}