config：添加TypeORM数据库连接配置

- 在AppModule中配置MySQL数据库连接
- 设置实体自动扫描路径
- 禁用synchronize以保护生产数据

src/app.module.ts

@@ -1,8 +1,10 @@
 import { Module } from '@nestjs/common';
 import { ConfigModule } from '@nestjs/config';
+import { TypeOrmModule } from '@nestjs/typeorm';
 import { AppController } from './app.controller';
 import { AppService } from './app.service';
 import { LoggerModule } from './core/utils/logger/logger.module';
+import { UsersModule } from './core/db/users/users.module';
 
 @Module({
   imports: [
@@ -11,6 +13,17 @@ import { LoggerModule } from './core/utils/logger/logger.module';
       envFilePath: '.env',
     }),
     LoggerModule,
+    TypeOrmModule.forRoot({
+      type: 'mysql',
+      host: process.env.DB_HOST,
+      port: parseInt(process.env.DB_PORT),
+      username: process.env.DB_USERNAME,
+      password: process.env.DB_PASSWORD,
+      database: process.env.DB_NAME,
+      entities: [__dirname + '/**/*.entity{.ts,.js}'],
+      synchronize: false,
+    }),
+    UsersModule,
   ],
   controllers: [AppController],
   providers: [AppService],