Update golangci-lint from v2.11.2 to v2.11.4 and fix new `modernize`
lint warnings:
- Use `strings.Builder` instead of string concatenation in loop
(`evaluator.go`)
- Use `atomic.Int64` instead of `int64` with atomic free functions
(`logchecker.go`, `timer_test.go`, `integration_test.go`)
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This PR was written with the help of Claude Opus 4.6
Co-authored-by: Claude (Opus 4.6) <noreply@anthropic.com>