feat(chess): add rank numbers (1-8) to board coordinates

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/chess/ChessBoard.kt

@@ -79,6 +79,12 @@ fun ChessBoard(
                             } else {
                                 null
                             },
+                        rankLabel =
+                            if (showCoordinates && file == 0) {
+                                (rank + 1).toString()
+                            } else {
+                                null
+                            },
                     )
                 }
             }
@@ -95,6 +101,7 @@ private fun ChessSquare(
     isLight: Boolean,
     size: Dp,
     coordinate: String?,
+    rankLabel: String? = null,
 ) {
     Box(
         modifier =
@@ -114,6 +121,20 @@ private fun ChessSquare(
             )
         }
 
+        // Show rank label (1-8) on left file
+        rankLabel?.let {
+            Text(
+                text = it,
+                fontSize = 10.sp,
+                fontWeight = FontWeight.Bold,
+                color = if (isLight) Color(0xFFB58863) else Color(0xFFF0D9B5),
+                modifier =
+                    Modifier
+                        .align(Alignment.TopStart)
+                        .padding(2.dp),
+            )
+        }
+
         // Show file coordinate (a-h) on bottom rank
         coordinate?.let {
             Text(

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/chess/InteractiveChessBoard.kt

@@ -117,6 +117,7 @@ fun InteractiveChessBoard(
                         val isLegalMove = legalMoves.contains(square)
 
                         val showCoord = if (flipped) rank == 7 else rank == 0
+                        val showRankLabel = if (flipped) file == 7 else file == 0
 
                         InteractiveChessSquare(
                             piece = piece,
@@ -125,6 +126,7 @@ fun InteractiveChessBoard(
                             isSelected = isSelected,
                             isLegalMove = isLegalMove,
                             showCoordinate = showCoord,
+                            showRankLabel = showRankLabel,
                             file = file,
                             rank = rank,
                             onClick = {
@@ -231,6 +233,7 @@ private fun InteractiveChessSquare(
     isSelected: Boolean,
     isLegalMove: Boolean,
     showCoordinate: Boolean,
+    showRankLabel: Boolean,
     file: Int,
     rank: Int,
     onClick: () -> Unit,
@@ -286,6 +289,20 @@ private fun InteractiveChessSquare(
             )
         }
 
+        // Show rank label (1-8) on left file
+        if (showRankLabel) {
+            Text(
+                text = (rank + 1).toString(),
+                fontSize = 10.sp,
+                fontWeight = FontWeight.Bold,
+                color = if (isLight) Color(0xFFB58863) else Color(0xFFF0D9B5),
+                modifier =
+                    Modifier
+                        .align(Alignment.TopStart)
+                        .padding(2.dp),
+            )
+        }
+
         // Show file coordinate (a-h) on bottom rank
         if (showCoordinate) {
             Text(