Remove connection form Context on close

Enhance DbManager with heartbeat SQL support

Added heartbeat SQL constants for default and Oracle databases, and implemented heartbeat checking logic for pooled connections.

Refactor config loading for ThinkOrm

Update ThinkOrm.php

Merge pull request #17 from JaguarJack/main

fix: 修复 DbManager::instance 类型错误

Update composer.json

Update Db.php

fix mongodb heartbeat

Merge pull request #14 from ichynul/main

使用容器时通过bind替换类，让`think\facade\Db`可正常使用

兼容旧配置