Move prepare script to build folder

build/prepare-production.js

@@ -0,0 +1,12 @@
+// What's all this?
+// When preparing your app for production, Astro needs to be built first.
+// Astro builds with the index file pointing to the wrong path for CSS, as it's using "/assets/" instead of "./assets/", that one dot is important.
+// This file will quickly fix that for you, also it's part of the `yarn build` command so you don't need to worry about it each time you build.
+var replace = require("replace");
+replace({
+    regex: "/assets/",
+    replacement: "./assets/",
+    paths: ['./app/index.html'],
+    recursive: true,
+    silent: true,
+});