fix: add defaultMessage fallback to requestErrorConfig formatMessage calls

Ensures a readable string is shown when the locale key is missing,
instead of the raw key id.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/requestErrorConfig.ts

@@ -79,12 +79,24 @@ export const errorConfig: RequestConfig = {
         // \`error.request\` 在浏览器中是 XMLHttpRequest 的实例，
         // 而在node.js中是 http.ClientRequest 的实例
         if (typeof navigator !== 'undefined' && !navigator.onLine) {
-          message.error(getIntl().formatMessage({ id: 'app.request.offline' }));
+          message.error(
+            getIntl().formatMessage({
+              id: 'app.request.offline',
+              defaultMessage:
+                'Network unavailable. Please check your connection and try again.',
+            }),
+          );
         } else {
           message.error('None response! Please retry.');
         }
       } else if (typeof navigator !== 'undefined' && !navigator.onLine) {
-        message.error(getIntl().formatMessage({ id: 'app.request.offline' }));
+        message.error(
+          getIntl().formatMessage({
+            id: 'app.request.offline',
+            defaultMessage:
+              'Network unavailable. Please check your connection and try again.',
+          }),
+        );
       } else {
         // 发送请求时出了点问题
         message.error('Request error, please retry.');