feat: add useAuth composable with user tier detection

resources/js/App.vue

@@ -3,5 +3,13 @@
 </template>
 
 <script setup>
+import { onMounted } from 'vue'
 import { RouterView } from 'vue-router'
+import { useAuth } from './composables/useAuth.js'
+
+const { fetchUser } = useAuth()
+
+onMounted(async () => {
+    await fetchUser()
+})
 </script>