fix: createMenu 增加详细错误返回，区分 WxErrorException 和通用异常

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

car-wash-miniapp/src/main/java/com/kym/miniapp/controller/WeixinMPController.java

@@ -104,10 +104,13 @@ public class WeixinMPController {
             log.info("创建菜单: {}", menuJson);
             String result = wxMpService.getMenuService().menuCreate(menuJson);
             log.info("菜单创建结果: {}", result);
-            return R.success("菜单创建成功");
+            return R.success(result);
         } catch (WxErrorException e) {
-            log.error("创建菜单失败", e);
-            return R.failed(-1, "创建失败: " + e.getMessage());
+            log.error("创建菜单失败: {}", e.getMessage(), e);
+            return R.failed(e.getError().getErrorCode(), e.getError().getErrorMsg());
+        } catch (Exception e) {
+            log.error("创建菜单异常", e);
+            return R.failed(500, e.getMessage());
         }
     }