c++版本支持熔断降级吗，demo里没看到相关的例子

## Issue Description

Type: *bug report* or *feature request*

### Describe what happened (or what feature you want)

### Describe what you expected to happen

### How to reproduce it (as minimally and precisely as possible)

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### Tell us your environment

### Anything else we need to know?

Start by reviewing the C++ demo and the existing Sentinel C++ implementation to determine whether circuit breaking or degradation is already supported. The issue provides no reproduction steps, environment, file names, or tests, so clarify the expected feature and define a demonstrable example before deciding what completion means.

Written by the indexing model from the issue text.