Add completed/abandoned shelves with status transitions

Items can be moved to Completed or Abandoned via card buttons.
Only active items appear in the default/category tabs; completed and
abandoned items are visible only in their respective shelf tabs.
Restore button moves items back to active.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backlogger/views.py

@@ -35,8 +35,11 @@ SORT_MAP = {
 def item_list(request):
     category = request.GET.get('category', '')
     sort = request.GET.get('sort', 'fav')
+    shelf = request.GET.get('shelf', Item.ACTIVE)
+    if shelf not in (Item.ACTIVE, Item.COMPLETED, Item.ABANDONED):
+        shelf = Item.ACTIVE
 
-    items = Item.objects.filter(user=request.user)
+    items = Item.objects.filter(user=request.user, status=shelf)
     if category:
         items = items.filter(category=category)
     items = items.order_by(*SORT_MAP.get(sort, SORT_MAP['fav']))
@@ -45,6 +48,7 @@ def item_list(request):
         'items': items,
         'category': category,
         'sort': sort,
+        'shelf': shelf,
         'categories': Item.CATEGORY_CHOICES,
     })
 
@@ -79,6 +83,18 @@ def item_edit(request, pk):
     return render(request, 'backlogger/item_form.html', {'form': form, 'action': 'Edit', 'item': item})
 
 
+@login_required
+def item_set_status(request, pk):
+    if request.method == 'POST':
+        item = get_object_or_404(Item, pk=pk, user=request.user)
+        new_status = request.POST.get('status')
+        if new_status in (Item.ACTIVE, Item.COMPLETED, Item.ABANDONED):
+            item.status = new_status
+            item.save(update_fields=['status', 'updated_at'])
+    next_url = request.POST.get('next') or reverse('backlogger:list')
+    return redirect(next_url)
+
+
 @login_required
 def item_delete(request, pk):
     if request.method == 'POST':