production runtime and mock removal

lib/usage.ts

@@ -117,7 +117,7 @@ export function providerLabel(provider?: GenerationProvider): string {
   if (provider === "evolink") return "EvoLink";
   if (provider === "seedance") return "Seedance";
   if (provider === "bailian") return "阿里云百炼";
-  if (provider === "mock") return "系统";
+  if (provider === "mock") return "历史任务";
   return "未知服务商";
 }