add admin ability to double card values

public/matrix.js

@@ -1,5 +1,7 @@
 "use strict"
 
+import { qs } from "./shared.js"
+
 function setup() {
   let highlighted
   document.addEventListener("click", (event) => {
@@ -18,6 +20,18 @@ function setup() {
     highlighted = card
     card.classList.add("highlight")
   })
+
+  window.addEventListener("message", ({ data }) => {
+    if (data !== "double") {
+      return
+    }
+    for (let card of qs(".card")) {
+      if (card.classList.contains("cat")) {
+        continue
+      }
+      card.textContent = parseInt(card.textContent) * 2
+    }
+  })
 }
 
 setup()