style(reward): 优化奖励中心金币图标

lib/pages/reward/reward_tasks_view.dart

@@ -149,7 +149,7 @@ class _Balance extends StatelessWidget {
           ),
         ),
         const SizedBox(width: AppDimens.spaceSm),
-        const RewardCoinIcon(size: 32),
+        const RewardCoinIcon(key: Key('reward-balance-coin-icon'), size: 32),
       ],
     );
     if (onOpenWallet == null) return content;