Handle deleted collection items

[fbacall]

Summary of changes

• Displays a "tombstone" where an item in a collection or learning path topic has been deleted.

Motivation and context

#1108

Opted not to delete the CollectionItem/LearningPathTopicItem because there could be useful context in the comment.

Screenshots

Checklist

• I have read and followed the CONTRIBUTING guide.
• I confirm that I have the authority necessary to make this contribution on behalf of its copyright owner and agree
  to license it to the TeSS codebase under the
  BSD license.

[Copilot]

Pull Request Overview

Adds support for displaying a “tombstone” overlay when a referenced resource has been deleted in collections or learning paths.

• Introduces fixtures and controller tests for learning paths, topics, and collections containing deleted items
• Updates views (_learning_path_topic_item, _collection_item, new _deleted_resource partial) to conditionally render a tombstone instead of missing resources
• Adds localization, CSS styles, Safe Navigation in models, and template changes for autocompleter

Reviewed Changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
test/fixtures/*.yml	Added fixtures for paths, topics, collections with deleted items
test/controllers/*_controller_test.rb	New tests for show/edit/update when resource is deleted
config/locales/en.yml	Added deleted_resource localization key
app/views/common/_deleted_resource.html.erb	New partial for deleted-item overlay
app/views/learning_path_topic_items/_*.html.erb	Render deleted-item partial when resource is missing
app/views/collection_items/_*.html.erb	Ditto for collections
app/views/public_activity/common/_add_item.html.erb	Fallback title for deleted resource
app/views/collections/_collection_items_form.erb	JSON form: handle missing resource title and URL
app/assets/stylesheets/masonry.scss	Styles for .deleted-item-overlay
app/assets/javascripts/templates/*.hbs	Autocompleter: show muted span if no URL
app/models/*_item.rb	Use &. for resource title and guard secondary activity

Comments suppressed due to low confidence (1)

test/fixtures/collection_items.yml:14

• [nitpick] Using a hardcoded large ID assumes the record doesn't exist, which can make tests brittle; consider using a fixture with no resource association or an explicit 'missing' fixture.

  resource_id: 9999999 # Lets hope this doesn't exist

[Copilot]

This assertion is duplicated; you can remove the extra assert_response :success for clarity.

Suggested change

assert_response :success

[Copilot]

[nitpick] Deleted resources are still rendered as links, which may lead to broken paths; consider rendering a non-clickable element (e.g. <span>) when the resource is missing.

Suggested change

	<%= t('activity.actions.add') %> <%= type.model_name.human.downcase %> <%= link_to activity.parameters[:resource_title] || t('deleted_resource'),
	polymorphic_path(type.model_name.singular.to_sym,
	id: activity.parameters[:resource_id]) %>
	<%= t('activity.actions.add') %> <%= type.model_name.human.downcase %>
	<% if activity.parameters[:resource_id].present? %>
	<%= link_to activity.parameters[:resource_title] || t('deleted_resource'),
	polymorphic_path(type.model_name.singular.to_sym, id: activity.parameters[:resource_id]) %>
	<% else %>
	<span><%= t('deleted_resource') %></span>
	<% end %>

[Copilot]

[nitpick] The partial mixes learning_path_topic_item and collection_item, which can be confusing; consider passing a generic item local to simplify and clarify variable usage.

Suggested change

	<% learning_path_topic_item ||= nil %>
	<% collection_item ||= learning_path_topic_item %>
	<% item ||= nil %>