feat: add AdminMemberTiers page, MemberBadge component, and SettingsLayout; refactor routes and sidebar for improved navigation

src/layouts/SettingsLayout.js

@@ -0,0 +1,16 @@
+import React from 'react';
+import { Outlet } from 'react-router-dom';
+import SettingsSidebar from '../components/SettingsSidebar';
+
+const SettingsLayout = () => {
+  return (
+    <div className="flex flex-col gap-6 lg:flex-row">
+      <SettingsSidebar />
+      <div className="flex-1 min-w-0">
+        <Outlet />
+      </div>
+    </div>
+  );
+};
+
+export default SettingsLayout;