feat(openai): 支持 gpt-5.3-codex-spark 并统一 gpt-5.3 到 codex 计费

backend/internal/service/pricing_service_test.go

@@ -0,0 +1,35 @@
+package service
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestGetModelPricing_Gpt53CodexSparkUsesGpt51CodexPricing(t *testing.T) {
+	sparkPricing := &LiteLLMModelPricing{InputCostPerToken: 1}
+	gpt53Pricing := &LiteLLMModelPricing{InputCostPerToken: 9}
+
+	svc := &PricingService{
+		pricingData: map[string]*LiteLLMModelPricing{
+			"gpt-5.1-codex": sparkPricing,
+			"gpt-5.3":       gpt53Pricing,
+		},
+	}
+
+	got := svc.GetModelPricing("gpt-5.3-codex-spark")
+	require.Same(t, sparkPricing, got)
+}
+
+func TestGetModelPricing_Gpt53CodexFallbackStillUsesGpt52Codex(t *testing.T) {
+	gpt52CodexPricing := &LiteLLMModelPricing{InputCostPerToken: 2}
+
+	svc := &PricingService{
+		pricingData: map[string]*LiteLLMModelPricing{
+			"gpt-5.2-codex": gpt52CodexPricing,
+		},
+	}
+
+	got := svc.GetModelPricing("gpt-5.3-codex")
+	require.Same(t, gpt52CodexPricing, got)
+}