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/TaskForm.jsx

@@ -14,6 +14,7 @@ const FLAG_COLORS = [
 
 function TaskForm({ onSubmit, onCancel, submitLabel = "Add" }) {
   const [title, setTitle] = useState('')
+  const [description, setDescription] = useState('')
   const [tags, setTags] = useState('')
   const [hours, setHours] = useState('')
   const [minutes, setMinutes] = useState('')
@@ -33,6 +34,7 @@ function TaskForm({ onSubmit, onCancel, submitLabel = "Add" }) {
 
     const taskData = {
       title: title.trim(),
+      description: description.trim() || null,
       tags: tagList && tagList.length > 0 ? tagList : null,
       estimated_minutes: totalMinutes > 0 ? totalMinutes : null,
       flag_color: flagColor
@@ -56,6 +58,18 @@ function TaskForm({ onSubmit, onCancel, submitLabel = "Add" }) {
         />
       </div>
 
+      {/* Description */}
+      <div>
+        <label className="block text-xs text-gray-400 mb-1">Description</label>
+        <textarea
+          value={description}
+          onChange={(e) => setDescription(e.target.value)}
+          placeholder="Optional task description..."
+          rows="3"
+          className="w-full px-3 py-2 bg-cyber-darker border border-cyber-orange/50 rounded text-gray-100 text-sm focus:outline-none focus:border-cyber-orange resize-y"
+        />
+      </div>
+
       {/* Tags */}
       <div>
         <label className="block text-xs text-gray-400 mb-1">Tags (comma-separated)</label>