feat(admin): 新增备份管理页

frontend/src/layouts/AdminLayout.tsx

@@ -163,6 +163,7 @@ const allNavGroups: NavGroup[] = [
       { key: '/roles', label: '角色权限', permission: 'role:manage' },
       { key: '/admin-users', label: '管理员账号', permission: 'admin_user:manage' },
       { key: '/payment-configs', label: '支付配置', permission: 'payment_config:list' },
+      { key: '/backups', label: '备份管理', permission: 'backup:view' },
       { key: '/audit-logs', label: '审计日志', permission: 'audit_log:view' },
     ],
   },
@@ -231,6 +232,7 @@ const sectionMeta: Record<string, { title: string; description: string }> = {
   },
   '/system-configs': { title: '系统配置', description: '维护首页、发布、订单与支付配置。' },
   '/payment-configs': { title: '支付配置', description: '维护主站支付商户、渠道与回调参数。' },
+  '/backups': { title: '备份管理', description: '查看备份健康状态并维护定时备份计划。' },
   '/audit-logs': { title: '审计日志', description: '查看高风险操作与变更记录。' },
 }