feat(backend): 优化通知推送，区分输赢并显示可用余额

- 赎回通知区分输赢：赢的仓位显示"赎回成功"，输的仓位显示"已结算（无收益）"
- 买入/卖出/赎回通知消息中添加钱包可用余额显示
- 新增多语言文案支持

Made-with: Cursor

backend/src/main/resources/i18n/messages_en.properties

@@ -13,6 +13,7 @@ notification.order.quantity=Quantity
 notification.order.amount=Amount
 notification.order.account=Account
 notification.order.time=Time
+notification.order.available_balance=Available Balance
 notification.order.error_info=Error Information
 notification.order.unknown_account=Unknown Account
 notification.order.calculate_failed=Calculation Failed
@@ -26,6 +27,13 @@ notification.redeem.position_count=Position Count
 notification.redeem.positions=Redeemed Positions
 notification.redeem.account=Account
 notification.redeem.time=Time
+notification.redeem.available_balance=Available Balance
+
+# Position Settled (No Return)
+notification.redeem.no_return.title=Position Settled (No Return)
+notification.redeem.no_return.info=Settlement Information
+notification.redeem.no_return.message=Market settled. Your prediction was incorrect. Redemption value is 0.
+notification.redeem.no_return.positions=Settled Positions
 
 # Auto Redeem related notifications
 notification.auto_redeem.disabled.title=Auto Redeem Disabled

backend/src/main/resources/i18n/messages_zh_CN.properties

@@ -13,6 +13,7 @@ notification.order.quantity=数量
 notification.order.amount=金额
 notification.order.account=账户
 notification.order.time=时间
+notification.order.available_balance=可用余额
 notification.order.error_info=错误信息
 notification.order.unknown_account=未知账户
 notification.order.calculate_failed=计算失败
@@ -26,6 +27,13 @@ notification.redeem.position_count=仓位数量
 notification.redeem.positions=赎回仓位
 notification.redeem.account=账户
 notification.redeem.time=时间
+notification.redeem.available_balance=可用余额
+
+# 仓位已结算（无收益）
+notification.redeem.no_return.title=仓位已结算（无收益）
+notification.redeem.no_return.info=结算信息
+notification.redeem.no_return.message=市场已结算，您的预测未命中，赎回价值为 0。
+notification.redeem.no_return.positions=结算仓位
 
 # 自动赎回相关通知
 notification.auto_redeem.disabled.title=自动赎回未开启

backend/src/main/resources/i18n/messages_zh_TW.properties

@@ -13,6 +13,7 @@ notification.order.quantity=數量
 notification.order.amount=金額
 notification.order.account=賬戶
 notification.order.time=時間
+notification.order.available_balance=可用餘額
 notification.order.error_info=錯誤信息
 notification.order.unknown_account=未知賬戶
 notification.order.calculate_failed=計算失敗
@@ -26,6 +27,13 @@ notification.redeem.position_count=倉位數量
 notification.redeem.positions=贖回倉位
 notification.redeem.account=賬戶
 notification.redeem.time=時間
+notification.redeem.available_balance=可用餘額
+
+# 倉位已結算（無收益）
+notification.redeem.no_return.title=倉位已結算（無收益）
+notification.redeem.no_return.info=結算信息
+notification.redeem.no_return.message=市場已結算，您的預測未命中，贖回價值為 0。
+notification.redeem.no_return.positions=結算倉位
 
 # 自動贖回相關通知
 notification.auto_redeem.disabled.title=自動贖回未開啟