Move all assets to assets directory

assets/js/pages/about.js

@@ -0,0 +1,7 @@
+export const aboutPage = () => ({
+  count: 0,
+
+  decrement() {
+    this.count--
+  }
+})

assets/js/pages/index.js

@@ -0,0 +1,7 @@
+export const indexPage = () => ({
+  count: 0,
+
+  increment() {
+    this.count++
+  }
+})