refactor(frontend): Reactivityで型を明示するように (#12791)

* refactor(frontend): Reactivityで型を明示するように

* fix: プロパティの参照が誤っているのを修正

* fix: 初期化の値を空配列に書き換えていた部分をnullに置き換え

packages/frontend/src/pages/avatar-decorations.vue

@@ -35,6 +35,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 <script lang="ts" setup>
 import { ref, computed } from 'vue';
+import * as Misskey from 'misskey-js';
 import MkButton from '@/components/MkButton.vue';
 import MkInput from '@/components/MkInput.vue';
 import MkTextarea from '@/components/MkTextarea.vue';
@@ -43,7 +44,7 @@ import { i18n } from '@/i18n.js';
 import { definePageMetadata } from '@/scripts/page-metadata.js';
 import MkFolder from '@/components/MkFolder.vue';
 
-const avatarDecorations = ref<any[]>([]);
+const avatarDecorations = ref<Misskey.entities.AdminAvatarDecorationsListResponse>([]);
 
 function add() {
 	avatarDecorations.value.unshift({