fix: 修复consumableImport.js路由级authMiddleware拦截所有/api请求的问题

consumableImport.js挂载在/api根路径，使用router.use(authMiddleware)
会拦截所有/api/*请求（包括公开路由如/api/auth/login），
导致登录等公开接口返回401。

修复方案：移除router.use(authMiddleware)，改为在每个具体路由上
单独添加authMiddleware中间件。

backend/routes/statistics.js

@@ -1,13 +1,14 @@
 const express = require('express');
 const router = express.Router();
 const { Op } = require('sequelize');
+const { authMiddleware } = require('../middleware/auth');
 const Device = require('../models/Device');
 const Rack = require('../models/Rack');
 const Room = require('../models/Room');
 const User = require('../models/User');
 const Ticket = require('../models/Ticket');
 
-router.get('/', async (req, res) => {
+router.get('/', authMiddleware, async (req, res) => {
   try {
     const now = new Date();
     const oneWeekAgo = new Date(now.getTime() - 7 * 24 * 60 * 60 * 1000);