feat(数据库配置): 添加PostgreSQL支持并更新相关配置

- 在.env.dev和.env.prod中添加PostgreSQL配置项
- 更新setting.py以支持PostgreSQL数据库连接
- 在DB_URI和DATABASES_URI方法中添加PostgreSQL处理逻辑
- 补充constant.py中的常量注释

backend/env/.env.dev

@@ -41,6 +41,13 @@ MYSQL_PASSWORD = "ServBay.dev"
 MYSQL_PORT = 3306
 MYSQL_DB_NAME = "fastapi_vue_admin"
 
+# PostgreSQL配置
+POSTGRESQL_HOST = "localhost"
+POSTGRESQL_USER = "postgres"
+POSTGRESQL_PASSWORD = 123456
+POSTGRESQL_PORT = 5432
+POSTGRESQL_DB_NAME = "fastapi_vue_admin"
+
 # Redis配置
 REDIS_ENABLE = True 
 REDIS_HOST = "localhost"