Remove Aevo exchange (retired)

- Delete exchange/aevo.go (AevoWS, aevoTickerMsg, aevoTickerData, etc.)
- scanner.go: remove ExAevo constant, fee rates, scan pair entries, shortName mapping
- main.go: remove aevoSymbols collection loop and TrackedSymbol usage

scanner.go

@@ -14,7 +14,6 @@ const (
 	ExHyperLiquid = "HyperLiquid"
 	ExBitget      = "Bitget"
 	ExDydx        = "dYdX"
-	ExAevo        = "Aevo"
 )
 
 // Fee rates (%) — taker fees per exchange
@@ -23,7 +22,6 @@ var feeRates = map[string]float64{
 	ExHyperLiquid: 0.035,
 	ExBitget:      0.040, // standard taker
 	ExDydx:        0.050, // dYdX v4 standard taker
-	ExAevo:        0.050, // Aevo standard taker
 }
 
 // Maker fee rates (%) — for limit orders
@@ -32,7 +30,6 @@ var makerFees = map[string]float64{
 	ExHyperLiquid: 0.015,
 	ExBitget:      0.020, // standard maker
 	ExDydx:        0.020,
-	ExAevo:        0.020,
 }
 
 // TickerCoins defines all coins we monitor.
@@ -67,7 +64,6 @@ func ScanArbWithFees(store *PriceStore, fees map[string]float64) []*ArbOpportuni
 		hlP := exMap[ExHyperLiquid]
 		bgP := exMap[ExBitget]
 		dyP := exMap[ExDydx]
-		aeP := exMap[ExAevo]
 
 		var pairs []struct {
 			profit float64
@@ -102,13 +98,9 @@ func ScanArbWithFees(store *PriceStore, fees map[string]float64) []*ArbOpportuni
 		addPair(ExBinance, ExHyperLiquid, bnP, hlP)
 		addPair(ExBinance, ExBitget, bnP, bgP)
 		addPair(ExBinance, ExDydx, bnP, dyP)
-		addPair(ExBinance, ExAevo, bnP, aeP)
 		addPair(ExHyperLiquid, ExBitget, hlP, bgP)
 		addPair(ExHyperLiquid, ExDydx, hlP, dyP)
-		addPair(ExHyperLiquid, ExAevo, hlP, aeP)
 		addPair(ExBitget, ExDydx, bgP, dyP)
-		addPair(ExBitget, ExAevo, bgP, aeP)
-		addPair(ExDydx, ExAevo, dyP, aeP)
 
 		if len(pairs) == 0 {
 			continue
@@ -163,8 +155,6 @@ func shortName(exchange string) string {
 		return "BG"
 	case ExDydx:
 		return "dYdX"
-	case ExAevo:
-		return "Ae"
 	}
 	return "??"
 }