fix: addStallBalance 使用 MessageUtils 替代硬编码中文

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

ruoyi-admin/src/main/java/com/ruoyi/app/service/WalletService.java

@@ -324,7 +324,7 @@ public class WalletService {
                     // 2. 获取摊位钱包
                     UserWallet stallWallet = userWalletService.selectByStoreId(storeId);
                     if (stallWallet == null) {
-                        throw new ServiceException("摊位钱包不存在");
+                        throw new ServiceException(MessageUtils.message("no.user.wallet.not.exist"));
                     }
 
                     // 3. 更新余额