feat(trader): add automatic balance sync every 30 minutes

## Summary
Automatically sync trader's initial_balance when exchange balance changes
significantly (>5%), eliminating the need for manual intervention after
deposits/withdrawals.

## Changes

### trader/auto_trader.go
- Add fields: lastBalanceSyncTime, database, userID
- Add autoSyncBalanceIfNeeded() method:
  * Check every 30 minutes (配合3分钟扫描周期，约10次扫描触发一次)
  * Query exchange balance via trader.GetBalance()
  * Update if change >5%
  * Log changes with emoji indicators
- Integrate into runCycle() before trading decisions

### manager/trader_manager.go
- Update NewAutoTrader() calls to pass database and userID
- Update method signatures:
  * addTraderFromDB()
  * AddTraderFromDB()
  * loadSingleTrader()

## Configuration

- Check interval: 30 minutes
- Change threshold: 5%
- Automatic detection and update

## Benefits

✅ 完全自动化，无需手动调用API
✅ 30分钟检查间隔，及时又不频繁
✅ 智能判断（变化>5%才更新）
✅ 充值/提现后自动更新initial_balance
✅ 前端P&L显示自动修正

## Example Logs

🔄 [DS-BF] 开始自动检查余额变化...
🔔 [DS-BF] 检测到余额大幅变化: 693.00 → 3000.00 USDT (333.33%)
✅ [DS-BF] 已自动同步余额到数据库

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

manager/trader_manager.go

@@ -181,7 +181,7 @@ func (tm *TraderManager) LoadTradersFromDatabase(database *config.Database) erro
 		}
 
 		// 添加到TraderManager
-		err = tm.addTraderFromDB(traderCfg, aiModelCfg, exchangeCfg, newsCfg, coinPoolURL, oiTopURL, maxDailyLoss, maxDrawdown, stopTradingMinutes, defaultCoins)
+		err = tm.addTraderFromDB(traderCfg, aiModelCfg, exchangeCfg, newsCfg, coinPoolURL, oiTopURL, maxDailyLoss, maxDrawdown, stopTradingMinutes, defaultCoins, database, traderCfg.UserID)
 		if err != nil {
 			log.Printf("❌ 添加交易员 %s 失败: %v", traderCfg.Name, err)
 			continue
@@ -193,7 +193,7 @@ func (tm *TraderManager) LoadTradersFromDatabase(database *config.Database) erro
 }
 
 // addTraderFromConfig 内部方法：从配置添加交易员（不加锁，因为调用方已加锁）
-func (tm *TraderManager) addTraderFromDB(traderCfg *config.TraderRecord, aiModelCfg *config.AIModelConfig, exchangeCfg *config.ExchangeConfig, newsCfg []config.NewsConfig, coinPoolURL, oiTopURL string, maxDailyLoss, maxDrawdown float64, stopTradingMinutes int, defaultCoins []string) error {
+func (tm *TraderManager) addTraderFromDB(traderCfg *config.TraderRecord, aiModelCfg *config.AIModelConfig, exchangeCfg *config.ExchangeConfig, newsCfg []config.NewsConfig, coinPoolURL, oiTopURL string, maxDailyLoss, maxDrawdown float64, stopTradingMinutes int, defaultCoins []string, database *config.Database, userID string) error {
 	if _, exists := tm.traders[traderCfg.ID]; exists {
 		return fmt.Errorf("trader ID '%s' 已存在", traderCfg.ID)
 	}
@@ -273,8 +273,8 @@ func (tm *TraderManager) addTraderFromDB(traderCfg *config.TraderRecord, aiModel
 		traderConfig.DeepSeekKey = aiModelCfg.APIKey
 	}
 
-	// 创建trader实例
+	// 创建trader实例（传入database和userID用于自动余额同步）
-	at, err := trader.NewAutoTrader(traderConfig)
+	at, err := trader.NewAutoTrader(traderConfig, database, userID)
 	if err != nil {
 		return fmt.Errorf("创建trader失败: %w", err)
 	}
@@ -298,7 +298,7 @@ func (tm *TraderManager) addTraderFromDB(traderCfg *config.TraderRecord, aiModel
 // AddTrader 从数据库配置添加trader (移除旧版兼容性)
 
 // AddTraderFromDB 从数据库配置添加trader
-func (tm *TraderManager) AddTraderFromDB(traderCfg *config.TraderRecord, aiModelCfg *config.AIModelConfig, exchangeCfg *config.ExchangeConfig, coinPoolURL, oiTopURL string, maxDailyLoss, maxDrawdown float64, stopTradingMinutes int, defaultCoins []string) error {
+func (tm *TraderManager) AddTraderFromDB(traderCfg *config.TraderRecord, aiModelCfg *config.AIModelConfig, exchangeCfg *config.ExchangeConfig, coinPoolURL, oiTopURL string, maxDailyLoss, maxDrawdown float64, stopTradingMinutes int, defaultCoins []string, database *config.Database, userID string) error {
 	tm.mu.Lock()
 	defer tm.mu.Unlock()
 
@@ -379,8 +379,8 @@ func (tm *TraderManager) AddTraderFromDB(traderCfg *config.TraderRecord, aiModel
 		traderConfig.DeepSeekKey = aiModelCfg.APIKey
 	}
 
-	// 创建trader实例
+	// 创建trader实例（传入database和userID用于自动余额同步）
-	at, err := trader.NewAutoTrader(traderConfig)
+	at, err := trader.NewAutoTrader(traderConfig, database, userID)
 	if err != nil {
 		return fmt.Errorf("创建trader失败: %w", err)
 	}
@@ -710,7 +710,7 @@ func (tm *TraderManager) LoadUserTraders(database *config.Database, userID strin
 		}
 
 		// 使用现有的方法加载交易员
-		err = tm.loadSingleTrader(traderCfg, aiModelCfg, exchangeCfg, coinPoolURL, oiTopURL, maxDailyLoss, maxDrawdown, stopTradingMinutes, defaultCoins)
+		err = tm.loadSingleTrader(traderCfg, aiModelCfg, exchangeCfg, coinPoolURL, oiTopURL, maxDailyLoss, maxDrawdown, stopTradingMinutes, defaultCoins, database, userID)
 		if err != nil {
 			log.Printf("⚠️ 加载交易员 %s 失败: %v", traderCfg.Name, err)
 		}
@@ -720,7 +720,7 @@ func (tm *TraderManager) LoadUserTraders(database *config.Database, userID strin
 }
 
 // loadSingleTrader 加载单个交易员（从现有代码提取的公共逻辑）
-func (tm *TraderManager) loadSingleTrader(traderCfg *config.TraderRecord, aiModelCfg *config.AIModelConfig, exchangeCfg *config.ExchangeConfig, coinPoolURL, oiTopURL string, maxDailyLoss, maxDrawdown float64, stopTradingMinutes int, defaultCoins []string) error {
+func (tm *TraderManager) loadSingleTrader(traderCfg *config.TraderRecord, aiModelCfg *config.AIModelConfig, exchangeCfg *config.ExchangeConfig, coinPoolURL, oiTopURL string, maxDailyLoss, maxDrawdown float64, stopTradingMinutes int, defaultCoins []string, database *config.Database, userID string) error {
 	// 处理交易币种列表
 	var tradingCoins []string
 	if traderCfg.TradingSymbols != "" {
@@ -789,8 +789,8 @@ func (tm *TraderManager) loadSingleTrader(traderCfg *config.TraderRecord, aiMode
 		traderConfig.DeepSeekKey = aiModelCfg.APIKey
 	}
 
-	// 创建trader实例
+	// 创建trader实例（传入database和userID用于自动余额同步）
-	at, err := trader.NewAutoTrader(traderConfig)
+	at, err := trader.NewAutoTrader(traderConfig, database, userID)
 	if err != nil {
 		return fmt.Errorf("创建trader失败: %w", err)
 	}

trader/auto_trader.go

@@ -118,10 +118,13 @@ type AutoTrader struct {
 	positionFirstSeenTime map[string]int64             // 持仓首次出现时间 (symbol_side -> timestamp毫秒)
 	lastPositions         map[string]*PositionSnapshot // 上一个周期的持仓快照 (symbol_side -> snapshot)
 	newsProcessor         []news.Provider              // 新闻
+	lastBalanceSyncTime   time.Time                    // 上次余额同步时间
+	database              *config.Database             // 数据库引用（用于自动更新余额）
+	userID                string                       // 用户ID
 }
 
 // NewAutoTrader 创建自动交易器
-func NewAutoTrader(traderConfig AutoTraderConfig) (*AutoTrader, error) {
+func NewAutoTrader(traderConfig AutoTraderConfig, db *config.Database, userID string) (*AutoTrader, error) {
 	// 设置默认值
 	if traderConfig.ID == "" {
 		traderConfig.ID = "default_trader"
@@ -261,6 +264,9 @@ func NewAutoTrader(traderConfig AutoTraderConfig) (*AutoTrader, error) {
 		positionFirstSeenTime: make(map[string]int64),
 		lastPositions:         make(map[string]*PositionSnapshot),
 		newsProcessor:         newsProcessor,
+		lastBalanceSyncTime:   time.Now(), // 初始化为当前时间
+		database:              db,
+		userID:                userID,
 	}, nil
 }
 
@@ -298,6 +304,64 @@ func (at *AutoTrader) Stop() {
 	log.Println("⏹ 自动交易系统停止")
 }
 
+// autoSyncBalanceIfNeeded 自动同步余额（每30分钟检查一次，变化>5%才更新）
+func (at *AutoTrader) autoSyncBalanceIfNeeded() {
+	// 距离上次同步不足30分钟，跳过
+	if time.Since(at.lastBalanceSyncTime) < 30*time.Minute {
+		return
+	}
+
+	log.Printf("🔄 [%s] 开始自动检查余额变化...", at.name)
+
+	// 查询实际余额
+	balanceInfo, err := at.trader.GetBalance()
+	if err != nil {
+		log.Printf("⚠️ [%s] 查询余额失败: %v", at.name, err)
+		at.lastBalanceSyncTime = time.Now() // 即使失败也更新时间，避免频繁重试
+		return
+	}
+
+	// 提取可用余额
+	var actualBalance float64
+	if availableBalance, ok := balanceInfo["available_balance"].(float64); ok && availableBalance > 0 {
+		actualBalance = availableBalance
+	} else if availableBalance, ok := balanceInfo["availableBalance"].(float64); ok && availableBalance > 0 {
+		actualBalance = availableBalance
+	} else if totalBalance, ok := balanceInfo["balance"].(float64); ok && totalBalance > 0 {
+		actualBalance = totalBalance
+	} else {
+		log.Printf("⚠️ [%s] 无法提取可用余额", at.name)
+		at.lastBalanceSyncTime = time.Now()
+		return
+	}
+
+	oldBalance := at.initialBalance
+	changePercent := ((actualBalance - oldBalance) / oldBalance) * 100
+
+	// 变化超过5%才更新
+	if math.Abs(changePercent) > 5.0 {
+		log.Printf("🔔 [%s] 检测到余额大幅变化: %.2f → %.2f USDT (%.2f%%)",
+			at.name, oldBalance, actualBalance, changePercent)
+
+		// 更新内存中的 initialBalance
+		at.initialBalance = actualBalance
+
+		// 更新数据库
+		if at.database != nil {
+			err := at.database.UpdateTraderInitialBalance(at.userID, at.id, actualBalance)
+			if err != nil {
+				log.Printf("❌ [%s] 更新数据库失败: %v", at.name, err)
+			} else {
+				log.Printf("✅ [%s] 已自动同步余额到数据库", at.name)
+			}
+		}
+	} else {
+		log.Printf("✓ [%s] 余额变化不大 (%.2f%%)，无需更新", at.name, changePercent)
+	}
+
+	at.lastBalanceSyncTime = time.Now()
+}
+
 // runCycle 运行一个交易周期（使用AI全权决策）
 func (at *AutoTrader) runCycle() error {
 	at.callCount++
@@ -329,7 +393,10 @@ func (at *AutoTrader) runCycle() error {
 		log.Println("📅 日盈亏已重置")
 	}
 
-	// 3. 收集交易上下文
+	// 3. 自动同步余额（每30分钟检查一次，充值/提现后自动更新）
+	at.autoSyncBalanceIfNeeded()
+
+	// 4. 收集交易上下文
 	ctx, err := at.buildTradingContext()
 	if err != nil {
 		record.Success = false