fix: use x and y instead of row and column for CursorPositionMsg

This means we're now 0-indexed, which is consistent with the rest of the
library.

cursor.go

@@ -3,13 +3,7 @@ package tea
 import "image"
 
 // CursorPositionMsg is a message that represents the terminal cursor position.
-type CursorPositionMsg struct {
-	// Row is the row number.
-	Row int
-
-	// Column is the column number.
-	Column int
-}
+type CursorPositionMsg image.Point
 
 // CursorStyle is a style that represents the terminal cursor.
 type CursorStyle int

key_test.go

@@ -64,7 +64,7 @@ func buildBaseSeqTests() []seqTest {
 		// position report having the same sequence. See [parseCsi] for more
 		// information.
 		if f3CurPosRegexp.MatchString(seq) {
-			st.msgs = []Msg{k, CursorPositionMsg{Row: 1, Column: int(key.Mod) + 1}}
+			st.msgs = []Msg{k, CursorPositionMsg{Y: 0, X: int(key.Mod)}}
 		}
 		td = append(td, st)
 	}

parse.go

@@ -256,7 +256,7 @@ func parseCsi(b []byte) (int, Msg) {
 		// This report may return a third parameter representing the page
 		// number, but we don't really need it.
 		if paramsLen >= 2 && csi.Param(0) != -1 && csi.Param(1) != -1 {
-			return i, CursorPositionMsg{Row: csi.Param(0), Column: csi.Param(1)}
+			return i, CursorPositionMsg{Y: csi.Param(0) - 1, X: csi.Param(1) - 1}
 		}
 	case 'm' | '<'<<parser.MarkerShift, 'M' | '<'<<parser.MarkerShift:
 		// Handle SGR mouse
@@ -275,7 +275,7 @@ func parseCsi(b []byte) (int, Msg) {
 	case 'R':
 		// Cursor position report OR modified F3
 		if paramsLen == 2 && csi.Param(0) != -1 && csi.Param(1) != -1 {
-			m := CursorPositionMsg{Row: csi.Param(0), Column: csi.Param(1)}
+			m := CursorPositionMsg{Y: csi.Param(0) - 1, X: csi.Param(1) - 1}
 			if csi.Param(0) == 1 && csi.Param(1)-1 <= int(ModMeta|ModShift|ModAlt|ModCtrl) {
 				// XXX: We cannot differentiate between cursor position report and
 				// CSI 1 ; <mod> R (which is modified F3) when the cursor is at the