fix(shared-ui): block click event after drag to prevent detail view opening

After a successful drag-and-drop, the browser fires a click event on
the source element. This was opening the detail view overlay instead of
completing the drop. Now a one-time click blocker is added after drag
ends to swallow the spurious click.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/shared-ui/src/dnd/drag-source.ts

@@ -108,6 +108,15 @@ export function dragSource(node: HTMLElement, options: DragSourceOptions) {
 				})
 			);
 			endDrag();
+			// Block the click event that fires after pointerup — prevents
+			// opening detail views when dropping an item.
+			const blocker = (ev: Event) => {
+				ev.stopPropagation();
+				ev.preventDefault();
+			};
+			node.addEventListener('click', blocker, { capture: true, once: true });
+			// Safety: remove blocker after a tick in case click doesn't fire
+			setTimeout(() => node.removeEventListener('click', blocker, { capture: true }), 0);
 		}
 		cleanup();
 	}