[Embeds] Format big numbers (#5087)

bskyembed/src/utils.ts

@@ -16,3 +16,13 @@ export function getRkey({uri}: {uri: string}): string {
   const at = new AtUri(uri)
   return at.rkey
 }
+
+const formatter = new Intl.NumberFormat('en-US', {
+  notation: 'compact',
+  maximumFractionDigits: 1,
+  roundingMode: 'trunc',
+})
+
+export function prettyNumber(number: number) {
+  return formatter.format(number)
+}