test(translator): skip replay target model allocation budget test under race detector

- Add race and non-race build-tagged test files in the Codex Claude translator package to expose race detector status.
- Skip TestConvertClaudeRequestToCodex_ResolvesReplayTargetModelOncePerRequest when the race detector is enabled to avoid flaky failures from random sync.Pool drops.

Closes: #6872

internal/translator/codex/claude/codex_claude_request_test.go

@@ -792,6 +792,10 @@ func TestConvertClaudeRequestToCodex_AssistantRoutedMetaSignatureToReasoningItem
 }
 
 func TestConvertClaudeRequestToCodex_ResolvesReplayTargetModelOncePerRequest(t *testing.T) {
+	if raceDetectorEnabled {
+		t.Skip("allocation budgets are not meaningful with race detector instrumentation")
+	}
+
 	const thinkingBlocks = 64
 	var body strings.Builder
 	body.WriteString(`{"messages":[{"role":"assistant","content":[`)

internal/translator/codex/claude/race_disabled_test.go

@@ -0,0 +1,5 @@
+//go:build !race
+
+package claude
+
+const raceDetectorEnabled = false

internal/translator/codex/claude/race_enabled_test.go

@@ -0,0 +1,5 @@
+//go:build race
+
+package claude
+
+const raceDetectorEnabled = true