feat: add 17 new cross-exchange pairs (BG↔HL)

Added: ALGO, PYTH, SAND, ADA, HBAR, IOTA, MINA, FET, WLD,
       SUI, APT, NEAR, FIL, DYDX, JUP, TIA, MOVE

Removed: pixel and VET (fake 195% spreads on testnet)

Also updated GetHLSize() to handle szDecimals for all new coins.

exchange/hyperliquid_trade.go

@@ -147,26 +147,28 @@ func (h *HyperLiquidTrade) GetBalance() (float64, error) {
 func GetHLSize(coin string, amountUSD, price float64) string {
 	sz := amountUSD / price
 	switch coin {
-	case "DOGE":
+	// integer sizes (szDecimals=0)
+	case "DOGE", "ONDO", "WIF", "ALGO", "PYTH", "SAND", "ADA", "HBAR",
+		"IOTA", "MINA", "FET", "JUP", "MOVE":
 		sz = math.Floor(sz)
-		if sz < 1 { sz = 1 }
+		if sz < 1 {
+			sz = 1
+		}
 		return fmt.Sprintf("%.0f", sz)
-	case "ONDO":
-		sz = math.Floor(sz)
-		if sz < 1 { sz = 1 }
-		return fmt.Sprintf("%.0f", sz)
-	case "OP":
-		sz = math.Floor(sz*10)/10
-		if sz < 0.1 { sz = 0.1 }
-		return fmt.Sprintf("%.1f", sz)
-	case "WIF":
-		sz = math.Floor(sz)
-		if sz < 1 { sz = 1 }
-		return fmt.Sprintf("%.0f", sz)
-	case "ARB":
-		sz = math.Floor(sz*10)/10
-		if sz < 0.1 { sz = 0.1 }
+	// 1 decimal (szDecimals=1)
+	case "OP", "ARB", "DYDX", "WLD", "SUI", "TIA", "NEAR", "FIL":
+		sz = math.Floor(sz*10) / 10
+		if sz < 0.1 {
+			sz = 0.1
+		}
 		return fmt.Sprintf("%.1f", sz)
+	// 2 decimals (szDecimals=2)
+	case "APT":
+		sz = math.Floor(sz*100) / 100
+		if sz < 0.01 {
+			sz = 0.01
+		}
+		return fmt.Sprintf("%.2f", sz)
 	default:
 		return fmt.Sprintf("%.4f", sz)
 	}