Add native Crystal exploration port and reference tooling

reference.html

@@ -0,0 +1,16 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta
+      name="viewport"
+      content="width=device-width,initial-scale=1,viewport-fit=cover"
+    />
+    <title>Crystal · Reference emulator</title>
+    <meta name="robots" content="noindex" />
+  </head>
+  <body>
+    <div id="app"></div>
+    <script type="module" src="/src/reference/main.ts"></script>
+  </body>
+</html>