refactor: use nuxt compatiable 4 folder

app/composables/store/user.ts

@@ -0,0 +1,34 @@
+import { acceptHMRUpdate, defineStore } from 'pinia'
+
+export const useUserStore = defineStore('user', () => {
+  /**
+   * Current name of the user.
+   */
+  const savedName = ref('')
+  const previousNames = ref(new Set<string>())
+
+  const usedNames = computed(() => Array.from(previousNames.value))
+  const otherNames = computed(() => usedNames.value.filter(name => name !== savedName.value))
+
+  /**
+   * Changes the current name of the user and saves the one that was used
+   * before.
+   *
+   * @param name - new name to set
+   */
+  function setNewName(name: string) {
+    if (savedName.value)
+      previousNames.value.add(savedName.value)
+
+    savedName.value = name
+  }
+
+  return {
+    setNewName,
+    otherNames,
+    savedName,
+  }
+})
+
+if (import.meta.hot)
+  import.meta.hot.accept(acceptHMRUpdate(useUserStore, import.meta.hot))