feat: real trading mode, auto-stop after 5 trades, HL testnet support

- config.json: test_mode=false, ready for sim/testnet trading
- trader.go: auto-stop after 5 real trades, exchange response logging,
  Stop()/Start() API, shuttingDown flag for graceful stop
- dashboard.go: POST /api/stop + POST /api/start endpoints,
  trading status in SSE stats
- exchange/hyperliquid.go: switch HL WS to testnet endpoint
- exchange/hyperliquid_trade.go: switch REST to testnet endpoint,
  support base64 + 32-byte EVM private keys
- main.go: listen on trader.StopCh (graceful, no process exit)
- scanner.go: trim TrackedCoins to only 6 core coins (DOGE/LINK/ONDO/OP/WIF/ARB)
- .gitignore: ignore main binary

exchange/hyperliquid.go

@@ -25,7 +25,7 @@ func NewHyperLiquidWS(tracked []string) *HyperLiquidWS {
 }
 // Run connects to HyperLiquid WS and streams mid prices.
 func (h *HyperLiquidWS) Run(updateFn func(coin string, price, bid, ask float64)) error {
-	conn := NewPriceConnector("wss://api.hyperliquid.xyz/ws", "HyperLiquid", 120*time.Second, 30*time.Second)
+	conn := NewPriceConnector("wss://api.hyperliquid-testnet.xyz/ws", "HyperLiquid", 120*time.Second, 30*time.Second)
 	conn.PingInterval = 45 * time.Second
 
 	conn.OnConnect = func() {

exchange/hyperliquid_trade.go

@@ -1,6 +1,7 @@
 package exchange
 
 import (
+	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
@@ -59,13 +60,27 @@ func NewHyperLiquidTrade(privateKeyHex, address string) (*HyperLiquidTrade, erro
 	if privateKeyHex == "" {
 		return &HyperLiquidTrade{client: &http.Client{Timeout: 10 * time.Second}}, nil
 	}
+
+	// Try hex decode first
 	keyBytes, err := hex.DecodeString(privateKeyHex)
 	if err != nil {
-		return nil, fmt.Errorf("decode private key: %w", err)
+		// Fallback to base64 decode
+		keyBytes, err = base64.StdEncoding.DecodeString(privateKeyHex)
+		if err != nil {
+			return nil, fmt.Errorf("decode private key: not valid hex or base64")
+		}
 	}
-	if len(keyBytes) != ed25519.PrivateKeySize {
-		return nil, fmt.Errorf("invalid private key length: %d (expected %d)", len(keyBytes), ed25519.PrivateKeySize)
+
+	// Accept both 32-byte (EVM) and 64-byte (Ed25519) keys
+	// 32-byte EVM keys are padded to 64 bytes for Ed25519
+	if len(keyBytes) == 32 {
+		// Use as Ed25519 seed — append the public key part
+		priv := ed25519.NewKeyFromSeed(keyBytes)
+		keyBytes = []byte(priv)
+	} else if len(keyBytes) != ed25519.PrivateKeySize {
+		return nil, fmt.Errorf("invalid private key length: %d (expected 32 or %d)", len(keyBytes), ed25519.PrivateKeySize)
 	}
+
 	return &HyperLiquidTrade{
 		PrivateKey: ed25519.PrivateKey(keyBytes),
 		Address:    address,
@@ -119,7 +134,7 @@ func (h *HyperLiquidTrade) PlaceMarketOrder(coin, side, sz string) (string, erro
 
 	bodyJSON, _ := json.Marshal(signed)
 
-	req, err := http.NewRequest("POST", "https://api.hyperliquid.xyz/exchange", strings.NewReader(string(bodyJSON)))
+	req, err := http.NewRequest("POST", "https://api.hyperliquid-testnet.xyz/exchange", strings.NewReader(string(bodyJSON)))
 	if err != nil {
 		return "", fmt.Errorf("create request: %w", err)
 	}