ui: update button for mobile

components/pwa/PwaBadge.client.vue

@@ -0,0 +1,17 @@
+<script setup>
+import { pwa } from '~/composables/pwa'
+</script>
+
+<template>
+  <button
+    v-if="pwa.needRefresh"
+    bg="fade" relative rounded
+    flex="~ gap-1 center" px3 py1 text-primary
+    @click="pwa.updateServiceWorker()"
+  >
+    <div i-ri-download-cloud-2-line />
+    <h2 flex="~ gap-2" items-center>
+      {{ $t('pwa.update_available_short') }}
+    </h2>
+  </button>
+</template>