feat: export ttfb series

Author: karlpauls

index.js

@@ -22,6 +22,7 @@ import {
   lcp,
   cls,
   inp,
+  ttfb,
   engagement,
 } from './series.js';
 import {
@@ -66,7 +67,10 @@ const series = {
   lcp,
   cls,
   inp,
+  ttfb,
   engagement,
 };
 
-export { DataChunks, utils, stats, series };
+export {
+  DataChunks, utils, stats, series,
+};