fix: register CSI ^ as scroll down alias

CSI Ps ^ is an alias for CSI Ps T (scroll down) added in upstream
xterm.js commit da4243c. Without this handler, the sequence is
silently ignored.

Fixes #1

Co-authored-by: Ona <no-reply@ona.com>

Author: csweichel

inputhandler.go

@@ -205,6 +205,7 @@ func NewInputHandler(
 	// CSI handlers — scroll
 	p.RegisterCsiHandler(FunctionIdentifier{Final: 'S'}, h.scrollUp)
 	p.RegisterCsiHandler(FunctionIdentifier{Final: 'T'}, h.scrollDown)
+	p.RegisterCsiHandler(FunctionIdentifier{Final: '^'}, h.scrollDown)
 	p.RegisterCsiHandler(FunctionIdentifier{Intermediates: " ", Final: '@'}, h.scrollLeft)
 	p.RegisterCsiHandler(FunctionIdentifier{Intermediates: " ", Final: 'A'}, h.scrollRight)
 	p.RegisterCsiHandler(FunctionIdentifier{Intermediates: "'", Final: '}'}, h.insertColumns)

inputhandler_csi_test.go

@@ -341,6 +341,16 @@ func TestScrollUpDown(t *testing.T) {
 			Input:    "AAA\x1b[2;1HBBB\x1b[1T",
 			Expected: Expectation{Row0: "", Row1: "AAA"},
 		},
+		{
+			Name:     "SD_scroll_down_caret_alias",
+			Input:    "AAA\x1b[2;1HBBB\x1b[1^",
+			Expected: Expectation{Row0: "", Row1: "AAA"},
+		},
+		{
+			Name:     "SD_scroll_down_caret_2",
+			Input:    "AAA\x1b[2;1HBBB\x1b[2^",
+			Expected: Expectation{Row0: "", Row1: ""},
+		},
 	}
 	for _, tc := range tests {
 		t.Run(tc.Name, func(t *testing.T) {