refactor: 集中管理配置常量并优化样式一致性

backend/config/index.js

@@ -0,0 +1,13 @@
+/**
+ * 配置统一导出
+ */
+
+const security = require('./security');
+const constants = require('./constants');
+
+module.exports = {
+  ...security,
+  ...constants,
+  security,
+  constants,
+};