refactor(frontend): use PageWithHeader instead of MkStickyContainer+MkPageHeader combination

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

@@ -4,8 +4,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 -->
 
 <template>
-<MkStickyContainer>
-	<template #header><MkPageHeader :actions="headerActions" :tabs="headerTabs"/></template>
+<PageWithHeader :actions="headerActions" :tabs="headerTabs">
 	<MkSpacer :contentMax="900">
 		<div class="_gaps">
 			<div :class="$style.decorations">
@@ -22,7 +21,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 			</div>
 		</div>
 	</MkSpacer>
-</MkStickyContainer>
+</PageWithHeader>
 </template>
 
 <script lang="ts" setup>