feat(billing): 完成异步结算与请求执行闭环

统一任务成功、Attempt 与结算 Outbox 的事务边界，增加多实例安全结算、人工复核、请求幂等与执行租约。钱包决策使用九位精确金额，并通过审计保护约束保留流水事实；同时补充管理接口、指标与 PostgreSQL 集成测试。

apps/api/internal/clients/openai_request_params_test.go

@@ -60,6 +60,23 @@ func TestValidateOpenAIRequestParametersRejectsUnknownTopLevelField(t *testing.T
 	}
 }
 
+func TestValidateOpenAIRequestParametersAcceptsInternalSimulationAndAffinityFields(t *testing.T) {
+	body := map[string]any{
+		"model": "demo", "messages": []any{}, "simulation": true,
+		"simulationDurationMs": 5, "simulationUsage": map[string]any{"inputTokens": 10},
+		"cacheAffinityKey": "conversation-1",
+	}
+	if err := ValidateOpenAIRequestParameters("chat.completions", body); err != nil {
+		t.Fatalf("expected documented gateway extensions to remain accepted, got %v", err)
+	}
+	filtered := FilterOpenAIChatRequestBody(body)
+	for _, key := range []string{"simulation", "simulationDurationMs", "simulationUsage", "cacheAffinityKey"} {
+		if _, ok := filtered[key]; ok {
+			t.Fatalf("gateway-only field %q leaked upstream", key)
+		}
+	}
+}
+
 func TestResponsesFallbackMapsEquivalentCurrentParameters(t *testing.T) {
 	body, err := ResponsesRequestToChat(map[string]any{
 		"input": "hello", "store": false, "metadata": map[string]any{"trace": "1"},