Stack notifications everywhere

We had client-side notification stacking in the tray since launch, but now we want to stack notifications in the notifications page, in API responses and in email bundles.

test/controllers/notifications_controller_test.rb

@@ -10,18 +10,17 @@ class NotificationsControllerTest < ActionDispatch::IntegrationTest
 
     assert_response :success
     assert_kind_of Array, @response.parsed_body
-    assert @response.parsed_body.any? { |n| n["id"] == notifications(:logo_published_kevin).id }
+    assert @response.parsed_body.any? { |n| n["id"] == notifications(:logo_assignment_kevin).id }
   end
 
   test "index as JSON includes notification attributes" do
     get notifications_path, as: :json
 
-    notification = @response.parsed_body.find { |n| n["id"] == notifications(:logo_published_kevin).id }
+    notification = @response.parsed_body.find { |n| n["id"] == notifications(:logo_assignment_kevin).id }
 
-    assert_not_nil notification["title"]
-    assert_not_nil notification["body"]
     assert_not_nil notification["created_at"]
     assert_not_nil notification["card"]
     assert_not_nil notification["creator"]
+    assert_not_nil notification["unread_count"]
   end
 end