fix(drag-reorder): expand target column height during cross-column drag

When dragging a card into a different kanban column, the gap/slot
system shifts cards down via translateY but the column's max-height
constraint clips the bottom cards off-screen. The source column
already locks its height to prevent collapse, but the target column
was not expanded to accommodate the incoming card.

The target column and its task container now have their max-height
temporarily increased by the drag gap amount when a card enters.
Both are reset in cleanupDragShift on drag end or container change.

Author: ac8318740

src/bases/KanbanView.ts

@@ -36,6 +36,7 @@ export class KanbanView extends BasesViewBase {
 	private dragContainer: HTMLElement | null = null; // Container holding siblings during drag
 	private currentInsertionIndex: number = -1; // Current gap/slot position
 	private dragSourceColumnEl: HTMLElement | null = null; // Source column element (height-locked during drag)
+	private dragTargetColumnEl: HTMLElement | null = null; // Target column element (max-height expanded during drag)
 	private draggedSourceColumns: Map<string, string> = new Map(); // Track source column per task for batch operations
 	private draggedSourceSwimlanes: Map<string, string> = new Map(); // Track source swimlane per task for batch operations
 	private taskInfoCache = new Map<string, TaskInfo>();
@@ -1541,9 +1542,22 @@ export class KanbanView extends BasesViewBase {
 							: 60;
 						const gapStr = getComputedStyle(container).gap;
 						const gap = parseFloat(gapStr) || 4;
-						container.style.setProperty("--tn-drag-gap", `${draggedHeight + gap}px`);
+						const totalGap = draggedHeight + gap;
+						container.style.setProperty("--tn-drag-gap", `${totalGap}px`);
 						container.style.overflowY = "clip";
 
+						// Expand target column/cell max-height to accommodate the gap
+						// so shifted cards aren't clipped off the bottom
+						const parentCol = container.closest<HTMLElement>(
+							".kanban-view__column, .kanban-view__swimlane-column"
+						);
+						if (parentCol) {
+							const currentMax = parentCol.getBoundingClientRect().height;
+							parentCol.style.maxHeight = `${currentMax + totalGap}px`;
+							this.dragTargetColumnEl = parentCol;
+						}
+						container.style.maxHeight = "none";
+
 						const siblings = container.querySelectorAll<HTMLElement>(".kanban-view__card-wrapper");
 						for (const sib of siblings) {
 							if (!this.draggedTaskPaths.includes(sib.dataset.taskPath || "")) {
@@ -1803,6 +1817,7 @@ export class KanbanView extends BasesViewBase {
 		if (this.dragContainer) {
 			this.dragContainer.style.removeProperty("--tn-drag-gap");
 			this.dragContainer.style.overflowY = "";
+			this.dragContainer.style.maxHeight = "";
 			const wrappers = this.dragContainer.querySelectorAll<HTMLElement>(
 				".kanban-view__card-wrapper--drag-shift, .kanban-view__card-wrapper--shift-down"
 			);
@@ -1812,6 +1827,12 @@ export class KanbanView extends BasesViewBase {
 			this.dragContainer = null;
 		}
 
+		// Reset target column max-height
+		if (this.dragTargetColumnEl) {
+			this.dragTargetColumnEl.style.maxHeight = "";
+			this.dragTargetColumnEl = null;
+		}
+
 		// Also clean any wrappers on the entire board (safety net for cross-column)
 		this.boardEl?.querySelectorAll<HTMLElement>(
 			".kanban-view__card-wrapper--drag-shift, .kanban-view__card-wrapper--shift-down"