enhance(client): メニューの「もっと」からインスタンス情報を見れるように

packages/frontend/src/navbar.ts

 import { computed, reactive } from 'vue';
 import { $i } from './account';
 import { miLocalStorage } from './local-storage';
+import { openInstanceMenu } from './ui/_common_/common';
 import * as os from '@/os';
 import { i18n } from '@/i18n';
 import { ui } from '@/config';
@@ -121,6 +122,13 @@ export const navbarItemDef = reactive({
 			}], ev.currentTarget ?? ev.target);
 		},
 	},
+	about: {
+		title: i18n.ts.about,
+		icon: 'ti ti-info-circle',
+		action: (ev) => {
+			openInstanceMenu(ev);
+		},
+	},
 	reload: {
 		title: i18n.ts.reload,
 		icon: 'ti ti-refresh',