feat: support layouts (#56)

Co-authored-by: Anthony Fu <anthonyfu117@hotmail.com>

src/layouts/default.vue

@@ -0,0 +1,9 @@
+<template>
+  <main class="px-4 py-10 text-center text-teal-700 dark:text-gray-200">
+    <router-view />
+    <Footer />
+    <div class="mt-5 m-auto text-center opacity-25 text-sm">
+      [Default Layout]
+    </div>
+  </main>
+</template>