fix: 系统检查修复 — 布局一致性 + bug 修复

- 公告图片样式统一：圆角 $radius-md，间距 $space-sm
- 首页紧急公告弹窗样式改为 SCSS 变量
- 新增 modal-mask-high mixin 统一高层级弹窗
- admin/config.vue 添加 initialLoaded 守卫避免重复请求
- notifications/index.vue 添加 initialLoaded 守卫
- notification store 所有方法添加 try-catch 错误处理

client/src/stores/notification.ts

@@ -8,26 +8,42 @@ export const useNotificationStore = defineStore('notification', () => {
   const urgentNotifications = ref<Notification[]>([])
 
   async function fetchUnreadCount() {
-    const data = await api.getUnreadCount()
-    unreadCount.value = data.count
+    try {
+      const data = await api.getUnreadCount()
+      unreadCount.value = data.count
+    } catch {
+      // 静默失败，不影响页面
+    }
   }
 
   /** 获取未读的强提醒公告（首页弹窗用） */
   async function fetchUrgentNotifications() {
-    urgentNotifications.value = await api.getPinnedNotifications()
+    try {
+      urgentNotifications.value = await api.getPinnedNotifications()
+    } catch {
+      // 静默失败
+    }
   }
 
   async function markRead(id: number) {
-    await api.markRead(id)
-    if (unreadCount.value > 0) unreadCount.value--
-    // 从强提醒列表中移除
-    urgentNotifications.value = urgentNotifications.value.filter(n => n.id !== id)
+    try {
+      await api.markRead(id)
+      if (unreadCount.value > 0) unreadCount.value--
+      // 从强提醒列表中移除
+      urgentNotifications.value = urgentNotifications.value.filter(n => n.id !== id)
+    } catch {
+      // 静默失败
+    }
   }
 
   async function markAllRead() {
-    await api.markAllRead()
-    unreadCount.value = 0
-    urgentNotifications.value = []
+    try {
+      await api.markAllRead()
+      unreadCount.value = 0
+      urgentNotifications.value = []
+    } catch {
+      // 静默失败
+    }
   }
 
   return { unreadCount, urgentNotifications, fetchUnreadCount, fetchUrgentNotifications, markRead, markAllRead }