feat(qmc): support audio meta getter

algo/qmc/client/cover.go

@@ -0,0 +1,21 @@
+package client
+
+import (
+	"context"
+	"fmt"
+	"strconv"
+)
+
+func (c *QQMusic) AlbumCoverByID(ctx context.Context, albumID int) ([]byte, error) {
+	u := fmt.Sprintf("https://imgcache.qq.com/music/photo/album/%s/albumpic_%s_0.jpg",
+		strconv.Itoa(albumID%100),
+		strconv.Itoa(albumID),
+	)
+	return c.downloadFile(ctx, u)
+}
+
+func (c *QQMusic) AlbumCoverByMediaID(ctx context.Context, mediaID string) ([]byte, error) {
+	// original: https://y.gtimg.cn/music/photo_new/T002M000%s.jpg
+	u := fmt.Sprintf("https://y.gtimg.cn/music/photo_new/T002R500x500M000%s.jpg", mediaID)
+	return c.downloadFile(ctx, u)
+}