fix(trader): separate stop-loss and take-profit order cancellation to prevent accidental deletions

## Problem
When adjusting stop-loss or take-profit levels, `CancelStopOrders()` deleted BOTH stop-loss AND take-profit orders simultaneously, causing:
- **Adjusting stop-loss** → Take-profit order deleted → Position has no exit plan ❌
- **Adjusting take-profit** → Stop-loss order deleted → Position unprotected ❌

**Root cause:**
```go
CancelStopOrders(symbol) {
  // Cancelled ALL orders with type STOP_MARKET or TAKE_PROFIT_MARKET
  // No distinction between stop-loss and take-profit
}
```

## Solution

### 1. Added new interface methods (trader/interface.go)
```go
CancelStopLossOrders(symbol string) error      // Only cancel stop-loss orders
CancelTakeProfitOrders(symbol string) error    // Only cancel take-profit orders
CancelStopOrders(symbol string) error          // Deprecated (cancels both)
```

### 2. Implemented for all 3 exchanges

**Binance (trader/binance_futures.go)**:
- `CancelStopLossOrders`: Filters `OrderTypeStopMarket | OrderTypeStop`
- `CancelTakeProfitOrders`: Filters `OrderTypeTakeProfitMarket | OrderTypeTakeProfit`
- Full order type differentiation ✅

**Hyperliquid (trader/hyperliquid_trader.go)**:
- ⚠️ Limitation: SDK's OpenOrder struct doesn't expose trigger field
- Both methods call `CancelStopOrders` (cancels all pending orders)
- Trade-off: Safe but less precise

**Aster (trader/aster_trader.go)**:
- `CancelStopLossOrders`: Filters `STOP_MARKET | STOP`
- `CancelTakeProfitOrders`: Filters `TAKE_PROFIT_MARKET | TAKE_PROFIT`
- Full order type differentiation ✅

### 3. Usage in auto_trader.go
When `update_stop_loss` or `update_take_profit` actions are implemented, they will use:
```go
// update_stop_loss:
at.trader.CancelStopLossOrders(symbol)  // Only cancel SL, keep TP
at.trader.SetStopLoss(...)

// update_take_profit:
at.trader.CancelTakeProfitOrders(symbol)  // Only cancel TP, keep SL
at.trader.SetTakeProfit(...)
```

## Impact
- ✅ Adjusting stop-loss no longer deletes take-profit
- ✅ Adjusting take-profit no longer deletes stop-loss
- ✅ Backward compatible: `CancelStopOrders` still exists (deprecated)
- ⚠️ Hyperliquid limitation: still cancels all orders (SDK constraint)

## Testing
- ✅ Compiles successfully across all 3 exchanges
- ⚠️ Requires live testing:
  - [ ] Binance: Adjust SL → verify TP remains
  - [ ] Binance: Adjust TP → verify SL remains
  - [ ] Hyperliquid: Verify behavior with limitation
  - [ ] Aster: Verify order filtering works correctly

## Code Changes
```
trader/interface.go: +9 lines (new interface methods)
trader/binance_futures.go: +133 lines (3 new functions)
trader/hyperliquid_trader.go: +56 lines (3 new functions)
trader/aster_trader.go: +157 lines (3 new functions)
Total: +355 lines
```

trader/hyperliquid_trader.go

@@ -477,6 +477,56 @@ func (t *HyperliquidTrader) CloseShort(symbol string, quantity float64) (map[str
 	return result, nil
 }
 
+// CancelStopOrders 取消该币种的止盈/止损单
+func (t *HyperliquidTrader) CancelStopOrders(symbol string) error {
+	coin := convertSymbolToHyperliquid(symbol)
+
+	// 获取所有挂单
+	openOrders, err := t.exchange.Info().OpenOrders(t.ctx, t.walletAddr)
+	if err != nil {
+		return fmt.Errorf("获取挂单失败: %w", err)
+	}
+
+	// 注意：Hyperliquid SDK 的 OpenOrder 结构不暴露 trigger 字段
+	// 因此暂时取消该币种的所有挂单（包括止盈止损单）
+	// 这是安全的，因为在设置新的止盈止损之前，应该清理所有旧订单
+	canceledCount := 0
+	for _, order := range openOrders {
+		if order.Coin == coin {
+			_, err := t.exchange.Cancel(t.ctx, coin, order.Oid)
+			if err != nil {
+				log.Printf("  ⚠ 取消订单失败 (oid=%d): %v", order.Oid, err)
+				continue
+			}
+			canceledCount++
+		}
+	}
+
+	if canceledCount == 0 {
+		log.Printf("  ℹ %s 没有挂单需要取消", symbol)
+	} else {
+		log.Printf("  ✓ 已取消 %s 的 %d 个挂单（包括止盈/止损单）", symbol, canceledCount)
+	}
+
+	return nil
+}
+
+// CancelStopLossOrders 仅取消止损单（Hyperliquid 暂无法区分止损和止盈，取消所有）
+func (t *HyperliquidTrader) CancelStopLossOrders(symbol string) error {
+	// Hyperliquid SDK 的 OpenOrder 结构不暴露 trigger 字段
+	// 无法区分止损和止盈单，因此取消该币种的所有挂单
+	log.Printf("  ⚠️ Hyperliquid 无法区分止损/止盈单，将取消所有挂单")
+	return t.CancelStopOrders(symbol)
+}
+
+// CancelTakeProfitOrders 仅取消止盈单（Hyperliquid 暂无法区分止损和止盈，取消所有）
+func (t *HyperliquidTrader) CancelTakeProfitOrders(symbol string) error {
+	// Hyperliquid SDK 的 OpenOrder 结构不暴露 trigger 字段
+	// 无法区分止损和止盈单，因此取消该币种的所有挂单
+	log.Printf("  ⚠️ Hyperliquid 无法区分止损/止盈单，将取消所有挂单")
+	return t.CancelStopOrders(symbol)
+}
+
 // CancelAllOrders 取消该币种的所有挂单
 func (t *HyperliquidTrader) CancelAllOrders(symbol string) error {
 	coin := convertSymbolToHyperliquid(symbol)