怎样可以手动开启或者关闭某个资源的熔断开关？

当前系统对 **缓存服务** 做了熔断，但是 **缓存服务** 何时可用需要我们自己的系统控制，而不是被 sentinel 设置的的熔断时间所固定。可以理解成 熔断时间只是一个兜底的方案，可以实现吗？

Start by reviewing Sentinel's circuit-breaking behavior for cache-service resources and identify how circuit state is currently controlled. Define an external manual open/close mechanism while retaining the configured timeout as a fallback, then establish acceptance criteria and focused tests for both control paths.

Written by the indexing model from the issue text.