refactor: split into component and use global app store

components/header/AppHeader.vue

@@ -0,0 +1,21 @@
+<template>
+  <div
+    class="pb-1.5 border-b border-gray-100 dark:border-gray-800 flex justify-between items-center"
+  >
+    <h1 class="text-4xl font-bold">Simple QRCode Generator</h1>
+
+    <div class="flex gap-x-1">
+      <UButton
+        color="gray"
+        variant="ghost"
+        icon="i-uil-github"
+        aria-label="Github repo"
+        class="w-8 h-8"
+        target="_blank"
+        to="https://github.com/pihkaal/simple-qr"
+      />
+
+      <ThemeSwitcher />
+    </div>
+  </div>
+</template>