feat(hyperliquid): add stock symbol market data support

- Add Hyperliquid/XYZ symbol normalization tests and backend coverage

- Extend kline and market data lookup paths for US stock symbols

- Wire frontend data API types for stock-oriented market requests

trader/hyperliquid/symbol_conversion_test.go

@@ -0,0 +1,18 @@
+package hyperliquid
+
+import "testing"
+
+func TestConvertSymbolToHyperliquidXYZAliases(t *testing.T) {
+	cases := map[string]string{
+		"SAMSUNG-USDC":  "xyz:SMSN",
+		"SK-HYNIX-USDC": "xyz:SKHX",
+		"TSLAUSDT":      "xyz:TSLA",
+		"xyz:SMSN":      "xyz:SMSN",
+		"HYPEUSDT":      "HYPE",
+	}
+	for input, want := range cases {
+		if got := convertSymbolToHyperliquid(input); got != want {
+			t.Fatalf("convertSymbolToHyperliquid(%q) = %q, want %q", input, got, want)
+		}
+	}
+}