fix: 4 bugfixes for production readiness

1. GetHLSize: add minimum size checks (prevent size=0 when price > amount)
2. executeEntry: orphan position warning when leg1 close also fails after leg2
3. checkExit: keep position as close_failed on failure, retryClose on each Tick
4. persistTrade: sync instead of goroutine (prevent data loss on exit)

exchange/hyperliquid_trade.go

@@ -178,21 +178,39 @@ func GetHLSize(coin string, amountUSD, price float64) string {
 	switch coin {
 	case "DOGE":
 		sz = math.Floor(sz) // step=1, szDecimals=0
+		if sz < 1 {
+			sz = 1
+		}
 		return fmt.Sprintf("%.0f", sz)
 	case "LINK":
 		sz = math.Floor(sz*10) / 10 // step=0.1, szDecimals=1
+		if sz < 0.1 {
+			sz = 0.1
+		}
 		return fmt.Sprintf("%.1f", sz)
 	case "ONDO":
 		sz = math.Floor(sz) // step=1, szDecimals=0
+		if sz < 1 {
+			sz = 1
+		}
 		return fmt.Sprintf("%.0f", sz)
 	case "OP":
 		sz = math.Floor(sz*10) / 10 // step=0.1, szDecimals=1
+		if sz < 0.1 {
+			sz = 0.1
+		}
 		return fmt.Sprintf("%.1f", sz)
 	case "WIF":
 		sz = math.Floor(sz) // step=1, szDecimals=0
+		if sz < 1 {
+			sz = 1
+		}
 		return fmt.Sprintf("%.0f", sz)
 	case "ARB":
 		sz = math.Floor(sz*10) / 10 // step=0.1, szDecimals=1
+		if sz < 0.1 {
+			sz = 0.1
+		}
 		return fmt.Sprintf("%.1f", sz)
 	default:
 		return fmt.Sprintf("%.4f", sz)