refactor(backend): 将ApiUser模型重命名为Admin并更新相关引用

backend/test_models.js

@@ -0,0 +1,32 @@
+const models = require('./src/models');
+
+console.log('Available models:', Object.keys(models));
+console.log('User model exists:', !!models.User);
+console.log('Admin model exists:', !!models.Admin);
+
+if (models.User) {
+  console.log('User model table name:', models.User.tableName);
+}
+
+if (models.Admin) {
+  console.log('Admin model table name:', models.Admin.tableName);
+}
+
+// 测试数据库连接
+if (models.User && models.User.sequelize) {
+  models.User.sequelize.authenticate()
+    .then(() => {
+      console.log('Database connection successful');
+      return models.User.sequelize.query('SELECT id, username, user_type FROM users LIMIT 5;', { 
+        type: models.User.sequelize.QueryTypes.SELECT 
+      });
+    })
+    .then(result => {
+      console.log('Users data:', result);
+    })
+    .catch(err => {
+      console.error('Database error:', err.message);
+    });
+} else {
+  console.log('Sequelize instance not found');
+}