fix: 删除零成交误判逻辑 + 各种稳定性修复

- 删除: Bitget GetTradeFee 零成交检查（PlaceMarketOrder 成功即成交）
- 修复: GetTradeFee 加 1s 延迟 + 查不到返回 0（用配置估算费兜底）
- 修复: HL InitExchange 在 NewTrader 中提前调用，避免 szDecimals 延迟
- 修复: close_failed 30 次重试上限，超限标记 failed 并清理
- 修复: DB 恢复时校验 Legs 完整性，跳过非法记录
- 修复: checkScaleIn/checkExit nil guard 防 panic
- 修复: config.go 参数调整（手续费、阈值等）
- 移除: scanner.go 中 MEW/USTC 等低流动性币对
- 添加: 更详细的下单日志（szStr、amountUSD、price）
- 添加: bin/ 到 .gitignore

exchange/hyperliquid_trade.go

@@ -6,6 +6,7 @@ import (
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
+	"log"
 	"math"
 	"strconv"
 	"strings"
@@ -59,6 +60,13 @@ func NewHyperLiquidTrade(privateKeyHex, mainAddress, apiAddress string) (*HyperL
 	}, nil
 }
 
+// InitExchange ensures the HL exchange is initialized (fetches metadata, szDecimals, etc.).
+// Safe to call multiple times — no-op after first initialization.
+// Must be called before GetSize or PlaceMarketOrder for accurate size formatting.
+func (h *HyperLiquidTrade) InitExchange() error {
+	return h.initExchange()
+}
+
 func (h *HyperLiquidTrade) initExchange() error {
 	if h.exchange != nil {
 		return nil
@@ -142,9 +150,16 @@ func (h *HyperLiquidTrade) PlaceMarketOrder(coin, side, sz string) (string, erro
 	isBuy := side == "buy"
 	size, _ := strconv.ParseFloat(sz, 64)
 
+	// Find szDecimals for this coin
+	decimals := 4
+	if d, ok := h.szDecimals[coin]; ok {
+		decimals = d
+	}
+
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 
+	log.Printf("[Order] HL MarketOpen | coin=%s isBuy=%v size=%.*f szDecimals=%d slippage=0.05 px=nil", coin, isBuy, decimals, size, decimals)
 	result, err := h.exchange.MarketOpen(ctx, coin, isBuy, size, nil, 0.05, nil, nil)
 	if err != nil {
 		return "", fmt.Errorf("market open: %w", err)