fix(providers): surface import errors and refresh list on failed import

Tauri invoke rejects with the backend's serialized error string, not an
Error object, so reading `.message` produced an empty toast for every
failed live-config import. Route the rejection through
extractErrorMessage with a generic i18n fallback.

Also invalidate the providers query on import failure: the import
command can have visible side effects before erroring (e.g. GrokBuild
ensures its official entry prior to a failing import), and the list
must reflect them without a manual refresh.

src/components/providers/ProviderList.tsx

@@ -20,6 +20,7 @@ import { toast } from "sonner";
 import type { Provider } from "@/types";
 import type { AppId } from "@/lib/api";
 import { providersApi } from "@/lib/api/providers";
+import { extractErrorMessage } from "@/utils/errorUtils";
 import { useDragSort } from "@/hooks/useDragSort";
 import {
   useOpenClawLiveProviderIds,
@@ -239,8 +240,13 @@ export function ProviderList({
         toast.info(t("provider.noProviders"));
       }
     },
-    onError: (error: Error) => {
-      toast.error(error.message);
+    onError: (error: unknown) => {
+      // Tauri invoke 的 reject 值是后端序列化出的纯字符串而非 Error 对象，
+      // 取 .message 只会得到 undefined（空 toast）。
+      toast.error(extractErrorMessage(error) || t("settings.importFailed"));
+      // 导入失败前也可能已产生需要上屏的副作用：GrokBuild 官方登录态下点
+      // 导入，命令层会先补种官方条目、随后才因 live 不可导入而报错。
+      queryClient.invalidateQueries({ queryKey: ["providers", appId] });
     },
   });