feat: downloader task stats (#339)

internal/protocol/http/fetcher.go

@@ -105,6 +105,7 @@ func (f *Fetcher) Resolve(req *base.Request) error {
 		Range: false,
 		Files: []*base.FileInfo{},
 	}
+
 	if base.HttpCodePartialContent == httpResp.StatusCode || (base.HttpCodeOK == httpResp.StatusCode && httpResp.Header.Get(base.HttpHeaderAcceptRanges) == base.HttpHeaderBytes && strings.HasPrefix(httpResp.Header.Get(base.HttpHeaderContentRange), base.HttpHeaderBytes)) {
 		// 1.返回206响应码表示支持断点下载 2.不返回206但是Accept-Ranges首部并且等于bytes也表示支持断点下载
 		res.Range = true