Drive the Live Feed ticker from an entity queue

Problem/Motivation

The home page Live Feed ticker ships six headlines and six times typed straight into the Canvas page, with only the link bound to content. Every RightUp site shows the same six invented headlines for ever, and publishing an article never reaches the ticker.

Steps to reproduce

1. Install RightUp on the current 1.0.x-dev.
2. Open the home page and note the six Live Feed entries and their times.
3. Publish a new News article.
4. Reload the home page. The ticker still shows the same six typed entries; the new article is not in it.

Proposed resolution

Make the ticker content, curated with Entityqueue:

• entityqueue.entity_queue.live_feed: a simple queue an editor curates, taking News and Podcast nodes, up to 10.
• views.view.live_feed reads it. Queued items come first in the editor's order, then the newest published content fills the rest, so an empty queue still gives a full ticker. The query is DISTINCT, so a node never appears twice.
• A live_feed node view mode renders each row through Live Feed Item in Canvas (content templates for News and Podcast), binding the authored date, title and URL.
• The six hand-typed Live Feed Items on the home page (content/canvas_page/01-home.yml) are replaced by one block.views_block.live_feed-block_1 in the Live Feed items slot.
• entityqueue is declared explicitly in recipe.yml (install) and composer.json (drupal/entityqueue: ^1.7). It was already installed through varbase_content_base, but RightUp now depends on it directly.

No default content is added. A simple queue's subqueue cannot be shipped: importing the queue makes Entityqueue create the subqueue with a freshly generated UUID (Simple::onQueuePostSave()), so a subqueue file with a fixed UUID can never match. default_content then INSERTs and the install dies on a duplicate key on entity_subqueue.name. This is deterministic. Falling back to the latest content is what keeps the ticker populated without shipping content.

Adds varbase-e2e coverage: tests/features/08-content-homepage/08-02-homepage-live-feed.feature (10 scenarios) and tests/step-definitions/live-feed.steps.js.

Depends on #3624018 in the theme, which must merge first. Without it the views wrappers are not dissolved and the ticker renders as a stacked list rather than a single line. It also adds the timestamp input the Live Feed Item binding uses.

Remaining tasks

• ✅ File an issue
• ✅ Addition/Change/Update/Fix
• ❌ Testing to ensure no regression
• ❌ Automated unit/functional testing coverage: the varbase-e2e suite has not had a green run yet. It was written against a site that was mid-reinstall, so all 10 scenarios failed on the environment rather than on the feature. --dry-run is clean (10 scenarios, 55 steps, 0 undefined). It needs a real run.
• ➖ Developer Documentation support
• ➖ User Guide Documentation support
• ➖ UX/UI designer responsibilities
• ➖ Accessibility and Readability
• ❌ Let content_editor curate the queue: varbase_content_base grants manipulate all entityqueues only to content_admin and site_admin, so an editor cannot pin an item today.
• ❌ Reviewed by a human
• ❌ Code review by maintainers
• ❌ Full testing and approval
• ❌ Credit contributors
• ❌ Review with the product owner
• ❌ Update Release Notes
• ❌ Release

User interface changes

• The home page ticker shows real, current content instead of six fixed headlines.
• A new Live feed queue under Structure, Entityqueues, for pinning and ordering ticker items.

API changes

• N/A

Data model changes

• New config: entityqueue.entity_queue.live_feed, views.view.live_feed, the live_feed node view mode with its News and Podcast displays and Canvas content templates, and the Canvas component configs for the views block and Live Feed Item.
• RightUp now requires drupal/entityqueue directly.

Release notes snippet

• The home page Live Feed ticker is now driven by an editor-curated entity queue, filled with the newest published content.