修复：区分通知加载失败与空列表

app/layouts/default.vue

@@ -244,6 +244,7 @@ const userItems = computed(() => [
 const {
   count: unreadCount,
   recent: recentMessages,
+  status: mailboxStatus,
   refresh: refreshMailbox,
 } = useMailbox();
 const mailboxOpen = ref(false);
@@ -672,7 +673,26 @@ useHead(() => ({
         :draggable="false"
       >
         <div class="mail-pop">
-          <div v-if="recentMessages.length" class="mail-pop-list">
+          <div
+            v-if="mailboxStatus === 'loading' || mailboxStatus === 'idle'"
+            class="mail-pop-empty"
+            role="status"
+          >
+            正在加载通知…
+          </div>
+          <div
+            v-else-if="mailboxStatus === 'error'"
+            class="mail-pop-empty"
+            role="alert"
+          >
+            <Icon name="lucide:triangle-alert" aria-hidden="true" />
+            <strong>通知暂时不可用</strong>
+            <span>加载失败，请重试</span>
+            <button type="button" class="mail-pop-foot" @click="refreshMailbox">
+              重新加载通知
+            </button>
+          </div>
+          <div v-else-if="recentMessages.length" class="mail-pop-list">
             <button
               v-for="message in recentMessages"
               :key="message.id"