Feature: Add position details to Trade History

Add missing fields to TradeOutcome:
- Quantity: Position size
- Leverage: Leverage multiplier
- PositionValue: Total position value (quantity × openPrice)
- MarginUsed: Margin required (positionValue / leverage)
This provides complete trade information for analysis and display.
Co-Authored-By: tinkle-community <tinklefund@gmail.com>

logger/decision_logger.go

@@ -271,10 +271,14 @@ type Statistics struct {
 type TradeOutcome struct {
 	Symbol        string    `json:"symbol"`         // 币种
 	Side          string    `json:"side"`           // long/short
+	Quantity      float64   `json:"quantity"`       // 仓位数量
+	Leverage      int       `json:"leverage"`       // 杠杆倍数
 	OpenPrice     float64   `json:"open_price"`     // 开仓价
 	ClosePrice    float64   `json:"close_price"`    // 平仓价
+	PositionValue float64   `json:"position_value"` // 仓位价值（quantity × openPrice）
+	MarginUsed    float64   `json:"margin_used"`    // 保证金使用（positionValue / leverage）
 	PnL           float64   `json:"pn_l"`           // 盈亏（USDT）
-	PnLPct      float64   `json:"pn_l_pct"`      // 盈亏百分比
+	PnLPct        float64   `json:"pn_l_pct"`       // 盈亏百分比（相对保证金）
 	Duration      string    `json:"duration"`       // 持仓时长
 	OpenTime      time.Time `json:"open_time"`      // 开仓时间
 	CloseTime     time.Time `json:"close_time"`     // 平仓时间
@@ -426,8 +430,12 @@ func (l *DecisionLogger) AnalyzePerformance(lookbackCycles int) (*PerformanceAna
 					outcome := TradeOutcome{
 						Symbol:        symbol,
 						Side:          side,
+						Quantity:      quantity,
+						Leverage:      leverage,
 						OpenPrice:     openPrice,
 						ClosePrice:    action.Price,
+						PositionValue: positionValue,
+						MarginUsed:    marginUsed,
 						PnL:           pnl,
 						PnLPct:        pnlPct,
 						Duration:      action.Timestamp.Sub(openTime).String(),