Add three new features to v0.1.5

1. Make parent cards draggable with all subtasks
   - Parent cards can now be dragged between columns
   - All descendants are automatically moved with the parent
   - Added isParent flag to drag/drop dataTransfer

2. Add Expand All / Collapse All buttons to Kanban view
   - Added global expandedCards state management
   - New buttons in Kanban header with ChevronsDown/Up icons
   - Allows quick expansion/collapse of all parent cards

3. Add description field to tasks
   - Added description textarea to TaskForm component
   - Added description edit option to TaskMenu component
   - Description displays in both TreeView and KanbanView
   - Shows below metadata in italic gray text
   - Backend already supported description field

frontend/src/components/TreeView.jsx

@@ -80,6 +80,7 @@ function TaskNode({ task, projectId, onUpdate, level = 0 }) {
         project_id: parseInt(projectId),
         parent_task_id: task.id,
         title: taskData.title,
+        description: taskData.description,
         status: 'backlog',
         tags: taskData.tags,
         estimated_minutes: taskData.estimated_minutes,
@@ -187,6 +188,13 @@ function TaskNode({ task, projectId, onUpdate, level = 0 }) {
                   )}
                 </div>
               )}
+
+              {/* Description */}
+              {task.description && (
+                <div className="mt-2 text-xs text-gray-400 italic">
+                  {task.description}
+                </div>
+              )}
             </div>
 
             {/* Actions */}
@@ -266,6 +274,7 @@ function TreeView({ projectId }) {
         project_id: parseInt(projectId),
         parent_task_id: null,
         title: taskData.title,
+        description: taskData.description,
         status: 'backlog',
         tags: taskData.tags,
         estimated_minutes: taskData.estimated_minutes,