sample: add Kanban Board demo with drag-and-drop functionality for cross-column card transfers

sample/common/src/commonMain/kotlin/App.kt

@@ -22,6 +22,7 @@ import androidx.navigation.compose.composable
 import androidx.navigation.compose.rememberNavController
 import navigation.AutoScrollDemoRoute
 import navigation.AxisLockedDragRoute
+import navigation.KanbanBoardRoute
 import navigation.ConditionalDropRoute
 import navigation.DragHandleReorderRoute
 import navigation.DropStrategiesPlaygroundRoute
@@ -34,6 +35,7 @@ import navigation.ReorderListRoute
 import theme.AppTheme
 import ui.AutoScrollDemoScreen
 import ui.AxisLockedDragScreen
+import ui.KanbanBoardScreen
 import ui.ConditionalDropScreen
 import ui.DragHandleReorderScreen
 import ui.DropStrategiesPlaygroundScreen
@@ -89,6 +91,9 @@ fun App() {
                         onNavigateToAutoScrollDemo = {
                             navController.navigate(AutoScrollDemoRoute)
                         },
+                        onNavigateToKanbanBoard = {
+                            navController.navigate(KanbanBoardRoute)
+                        },
                     )
                 }
                 composable<ItemToItemOneDirectionRoute> {
@@ -141,6 +146,11 @@ fun App() {
                         onBack = { navController.popBackStack() },
                     )
                 }
+                composable<KanbanBoardRoute> {
+                    KanbanBoardScreen(
+                        onBack = { navController.popBackStack() },
+                    )
+                }
             }
         }
     }

sample/common/src/commonMain/kotlin/navigation/Screen.kt

@@ -49,3 +49,6 @@ data object ConditionalDropRoute
 
 @Serializable
 data object AutoScrollDemoRoute
+
+@Serializable
+data object KanbanBoardRoute

sample/common/src/commonMain/kotlin/ui/HomeScreen.kt

@@ -64,6 +64,7 @@ fun HomeScreen(
     onNavigateToAxisLockedDrag: () -> Unit,
     onNavigateToConditionalDrop: () -> Unit,
     onNavigateToAutoScrollDemo: () -> Unit,
+    onNavigateToKanbanBoard: () -> Unit,
 ) {
     val scrollBehavior = TopAppBarDefaults.exitUntilCollapsedScrollBehavior()
 
@@ -148,6 +149,12 @@ fun HomeScreen(
             // -- Advanced Features --
             SectionHeader(title = "Advanced Features")
 
+            DemoListItem(
+                title = "Kanban Board",
+                description = "Cross-column card transfer with nested scroll",
+                icon = Icons.Rounded.GridView,
+                onClick = onNavigateToKanbanBoard,
+            )
             DemoListItem(
                 title = "Auto-Scroll Demo",
                 description = "Row, Grid, and ScrollState auto-scroll while dragging",