fix: use taker fees (BG 0.06%, HL 0.045%) + threshold 0.25%

All IOC market orders incur taker fees, not maker fees. Previous
makerFees (BG 0.02%, HL 0.015%) caused 0.10% threshold trades to
actually lose 0.11% per round trip.

Changes:
- scanner.go: makerFees → takerFees (BG 0.060, HL 0.045)
- dashboard.go: makerFees → takerFees
- types.go: makerFees → takerFees
- trader.go: makerFees → takerFees
- config.json: trade_threshold 0.1 → 0.25

trader.go

@@ -524,7 +524,7 @@ func (t *Trader) checkExit(pos *ArbPosition, bgP, hlP, diffPct float64, notifier
 
 	longPnl := (longCurrent - longAvg) / longAvg * 100
 	shortPnl := (shortAvg - shortCurrent) / shortAvg * 100
-	totalFees := 2 * (makerFees[ExBitget] + makerFees[ExHyperLiquid]) // 开仓 + 平仓手续费
+	totalFees := 2 * (takerFees[ExBitget] + takerFees[ExHyperLiquid]) // 开仓 + 平仓手续费
 	netPnl := longPnl + shortPnl - totalFees
 
 	// Convergence analysis