Problem

internal/scenarios/scenario_test.go used a helper that could call t.Fatalf from worker goroutines in runConcurrentScenario, which is unsafe for Go test failure semantics.

Changes

• split command execution into:
  • runCommand(...) returning (output, exitCode, error) without test-fatal behavior
  • mustRunCommand(...) for non-concurrent call sites that fail the test on execution error
• updated concurrent scenario workers to propagate execution errors through errCh instead of invoking t.Fatalf in goroutines

Validation

• go test ./internal/scenarios -count=1 -tags=scenario -v
• make prepush-full
• pre-push hook make prepush during git push