`clear` is not thread-safe wrt memory visibility

```cpp
void Timer::stop() {
this->clear = true;
}
```

`clear` as plain bool has no cross-thread synchronization so in theory the interval timer may run indefinitly, consider using `atomic_bool` and proper memory ordering.

Start at Timer::stop and the plain clear flag shown in the issue, then trace where the interval timer reads it. No file or test is named, so inspect the repository for the timer implementation and existing concurrency coverage. Done means the stop signal is reliably visible across threads and the interval timer cannot continue indefinitely after stopping.

Written by the indexing model from the issue text.