优化用户通知组件，增加通知列表容器样式以支持滚动，提升用户体验

src/layouts/components/UserNotification.vue

@@ -86,7 +86,8 @@ onBeforeUnmount(() => {
         </template>
       </VCardItem>
       <VDivider />
-      <div v-if="notificationList.length > 0">
+      <div class="notification-list-container">
+        <div v-if="notificationList.length > 0" class="notification-list">
           <VListItem v-for="(item, i) in notificationList" :key="i" lines="two" class="mb-1">
             <template #prepend>
               <VAvatar rounded>
@@ -112,6 +113,19 @@ onBeforeUnmount(() => {
           <VIcon icon="mdi-bell-sleep-outline" size="40" class="mb-3" />
           <div>{{ t('notification.empty') }}</div>
         </div>
+      </div>
     </VCard>
   </VMenu>
 </template>
+
+<style scoped>
+.notification-list-container {
+  max-height: 50vh;
+  overflow: hidden;
+}
+
+.notification-list {
+  max-height: 100%;
+  overflow-y: auto;
+}
+</style>