feat(hyperliquid): Add Unified Account support for Spot as Perp collateral (#1387)

This PR adds support for Hyperliquid's Unified Account mode where Spot USDC
balance can be used as collateral for Perpetual trading.

Changes:
- Add HyperliquidUnifiedAcct field to Exchange config (default: true)
- Update HyperliquidTrader to support unified account mode
- When enabled, Spot USDC balance is added to available trading balance
- Update API request/response structs for unified account toggle
- Update trader config propagation from exchange config

This aligns with Hyperliquid's roadmap to make Unified Account the default.

trader/auto_trader.go

@@ -63,9 +63,10 @@ type AutoTraderConfig struct {
 	KuCoinPassphrase string
 
 	// Hyperliquid configuration
-	HyperliquidPrivateKey string
-	HyperliquidWalletAddr string
-	HyperliquidTestnet    bool
+	HyperliquidPrivateKey  string
+	HyperliquidWalletAddr  string
+	HyperliquidTestnet     bool
+	HyperliquidUnifiedAcct bool // Unified Account mode: Spot USDC as Perp collateral
 
 	// Aster configuration
 	AsterUser       string // Aster main wallet address
@@ -260,7 +261,7 @@ func NewAutoTrader(config AutoTraderConfig, st *store.Store, userID string) (*Au
 		trader = kucoin.NewKuCoinTrader(config.KuCoinAPIKey, config.KuCoinSecretKey, config.KuCoinPassphrase)
 	case "hyperliquid":
 		logger.Infof("🏦 [%s] Using Hyperliquid trading", config.Name)
-		trader, err = hyperliquid.NewHyperliquidTrader(config.HyperliquidPrivateKey, config.HyperliquidWalletAddr, config.HyperliquidTestnet)
+		trader, err = hyperliquid.NewHyperliquidTrader(config.HyperliquidPrivateKey, config.HyperliquidWalletAddr, config.HyperliquidTestnet, config.HyperliquidUnifiedAcct)
 		if err != nil {
 			return nil, fmt.Errorf("failed to initialize Hyperliquid trader: %w", err)
 		}