修复：统一主题切换并升级依赖与验证流程

app/layouts/blank.vue

@@ -19,7 +19,7 @@ onMounted(() => siteConfig.load().catch(() => {}));
 </script>
 
 <template>
-  <!-- Keep the published CSS scope until its shared auth styles are migrated together. -->
+  <!-- 共享认证样式迁移前保留发布版作用域；主题入口遵循全站浅色/深色/跟随系统三态。 -->
   <div class="blank-layout" data-v-69ca9392>
     <header class="auth-topbar" data-v-69ca9392>
       <NuxtLink to="/" class="auth-logo" data-v-69ca9392>
@@ -29,14 +29,12 @@ onMounted(() => siteConfig.load().catch(() => {}));
         <button
           class="auth-theme"
           type="button"
-          :aria-label="theme.isDark.value ? '切换浅色模式' : '切换深色模式'"
+          :aria-label="`切换主题，当前${theme.label.value}`"
+          :title="`主题：${theme.label.value}（点击切换）`"
           data-v-69ca9392
           @click="theme.cycle"
         >
-          <i
-            :class="theme.isDark.value ? 'pi pi-moon' : 'pi pi-sun'"
-            data-v-69ca9392
-          />
+          <i :class="theme.icon.value" data-v-69ca9392 />
         </button>
         <NuxtLink
           v-if="route.path !== '/login'"