http: inject request ID for observability in direct read path

Add request_id.InjectToRequest() call to readUrlDirectToBuffer() for
consistency with ReadUrlAsStream path. This ensures full-chunk reads
carry the same tracing/correlation headers for server logs and metrics.

weed/util/http/http_global_client_util.go

@@ -613,6 +613,7 @@ func readUrlDirectToBuffer(ctx context.Context, fileUrl, jwt string, buffer []by
 		return 0, false, err
 	}
 	maybeAddAuth(req, jwt)
+	request_id.InjectToRequest(ctx, req)
 
 	r, err := GetGlobalHttpClient().Do(req)
 	if err != nil {