feat: add caching for backend objects

app/composables/useOfflineStatus.ts

@@ -0,0 +1,10 @@
+const _isOnline = ref(typeof navigator !== 'undefined' ? navigator.onLine : true)
+
+if (import.meta.client) {
+  window.addEventListener('online',  () => { _isOnline.value = true })
+  window.addEventListener('offline', () => { _isOnline.value = false })
+}
+
+export function useOfflineStatus() {
+  return { isOnline: readonly(_isOnline) }
+}