test(api): 显式启用异步执行验收 Worker

动态并发验收直接构造 Config 时需显式开启 AsyncQueueWorkerEnabled，避免零值 false 把该测试误变为仅入队模式。\n\n验证：gofmt、go test ./internal/httpapi -count=1。

apps/api/internal/httpapi/async_worker_acceptance_integration_test.go

@@ -54,6 +54,7 @@ func TestAsyncWorkerDynamicConcurrencyAcceptance(t *testing.T) {
 		JWTSecret:                         "test-secret",
 		BillingEngineMode:                 "observe",
 		CORSAllowedOrigin:                 "*",
+		AsyncQueueWorkerEnabled:           true,
 		AsyncWorkerHardLimit:              256,
 		AsyncWorkerRefreshIntervalSeconds: 1,
 	}, db, slog.New(slog.NewTextHandler(io.Discard, nil))))