chore: 统一代码风格并配置ESLint和Prettier

配置ESLint和Prettier规则
添加前端和后端的忽略文件
统一代码格式和缩进
修复代码风格问题

backend/package.json

@@ -7,7 +7,11 @@
     "dev": "nodemon server.js",
     "create-indexes": "node create_indexes.js",
     "check-indexes": "node create_indexes.js check",
-    "drop-indexes": "node create_indexes.js drop"
+    "drop-indexes": "node create_indexes.js drop",
+    "lint": "eslint . --ext js --report-unused-disable-directives --max-warnings 0",
+    "lint:fix": "eslint . --ext js --fix",
+    "format": "prettier --write \"**/*.js\"",
+    "format:check": "prettier --check \"**/*.js\""
   },
   "dependencies": {
     "axios": "^1.13.4",
@@ -31,8 +35,15 @@
     "xlsx": "^0.18.5"
   },
   "devDependencies": {
+    "eslint": "^9.39.2",
+    "eslint-config-prettier": "^10.1.8",
+    "eslint-plugin-prettier": "^5.5.5",
+    "eslint-plugin-react": "^7.37.5",
+    "eslint-plugin-react-hooks": "^7.0.1",
+    "eslint-plugin-react-refresh": "^0.5.0",
     "jest": "^30.2.0",
     "nodemon": "^3.0.1",
+    "prettier": "^3.8.1",
     "supertest": "^7.1.4"
   }
 }