根据环境变量优化数据库连接配置，简化生产和开发环境下的实体、迁移和订阅者文件路径判断逻辑。

src/config/database.ts

@@ -2,6 +2,8 @@ import { DataSource } from 'typeorm'
 import { FastifyInstance } from 'fastify'
 
 export const createDataSource = (app: FastifyInstance) => {
+  const isProd = process.env.NODE_ENV === 'production'
+
   return new DataSource({
     type: 'mysql',
     host: app.config.DB_HOST,
@@ -11,14 +13,14 @@ export const createDataSource = (app: FastifyInstance) => {
     database: app.config.DB_DATABASE,
     synchronize: true,
     logging: false,
-    entities: app.config.NODE_ENV === 'production'
+    entities: isProd
       ? ['dist/entities/*.entity.js']
       : ['src/entities/*.entity.ts'],
-    migrations: app.config.NODE_ENV === 'production'
+    migrations: isProd
       ? ['dist/migrations/**/*.js']
       : ['src/migrations/**/*.ts'],
-    subscribers: app.config.NODE_ENV === 'production'
+    subscribers: isProd
       ? ['dist/subscribers/**/*.js']
-      : ['src/subscribers/**/*.ts'],
+      : ['src/subscribers/**/*.ts']
   })
 }