Delete tasks from the board

Adds DELETE /api/orgboard/tasks/{id} (WorkTasks permission) and a "Delete task" button
in the task drawer (with confirm). Children are detached (kept as top-level) rather than
deleted; status-transition history is dropped. There was previously no way to remove a task.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/src/pages/BoardPage.tsx

@@ -8,7 +8,7 @@ import {
   useSensors,
   type DragEndEvent,
 } from '@dnd-kit/core'
-import { Bot, Plus } from 'lucide-react'
+import { Bot, Plus, Trash2 } from 'lucide-react'
 import { toast } from 'sonner'
 import { AppShell } from '@/components/AppShell'
 import { Badge } from '@/components/ui/badge'
@@ -554,6 +554,21 @@ function TaskDrawer({
             </div>
           </div>
         )}
+
+        <div className="mt-2 border-t pt-4">
+          <Button
+            variant="destructive"
+            size="sm"
+            disabled={busy}
+            onClick={() => {
+              if (window.confirm(`Delete "${task.title}"? This can't be undone.`)) {
+                act(() => api.del(`/api/orgboard/tasks/${task.id}`), 'Task deleted.').then(onClose)
+              }
+            }}
+          >
+            <Trash2 data-icon="inline-start" /> Delete task
+          </Button>
+        </div>
       </SheetContent>
     </Sheet>
   )