Add -race flag to CI test runs

## Priority: Medium

### Description

The codebase has a mutex guarding global state (`sccMu`) and stdout redirection — exactly the kind of code where race conditions hide. However, CI (`ci.yml:23`) runs tests without the race detector:

```yaml
- run: go test ./... -count=1
```

### Suggested fix

Change CI and pre-commit hook test commands to:

```
go test -race ./... -count=1
```