期望增加afterAuth

### 建议增加的新功能:
1. 期望在SaServletFilter中新增afterAuth属性
2. 期望在SaServletFilter中新增finalRun属性

### 应用场景阐述：

1. 用于在认证完后执行自定义函数，例如保存登录日志？
2. 用于在chain.doFilter(request, response);后置执行，例如，清除线程上下文之类的

< 备注：请尽量详细描述功能应用场景 >

Start with the SaServletFilter entry point and trace its authentication and request-chain lifecycle. Determine where an afterAuth callback and a finalRun callback would run based on the stated scenarios. Done means both properties are supported with the requested timing and their behavior is covered by the project's existing verification approach.

Written by the indexing model from the issue text.