Screen-reader context for generic links, new-tab warnings, and the footer and header per the design

Problem/Motivation

On a fresh Horizon Aid install, Editoria11y flags 49 generic "Learn More" links, LinkedIn links that open a new window without warning, a skipped heading ("Member for") and an unnamed avatar link.

The footer and header also differ from the design: the social icon set and order, the Quicklinks, and the underline running the full column width on hover and focus of Learn, Explore, Impact and Act.

Steps to reproduce

1. Install Drupal CMS with the Horizon Aid site template.
2. Log in and visit /programs and /about with Editoria11y on.
3. Hover the footer links.

Proposed resolution

• "Learn More" links and buttons read the card title to screen readers (visually hidden). Visible text is unchanged. New optional label_context prop on the button component.
• Every external link opens in a new tab with rel="noopener noreferrer" and a hidden "(opens in a new tab)".
• Footer: the design's social icons in design order (Facebook, Instagram, LinkedIn, X), one Quicklinks list, underline only under the label, visible focus ring. Header: link weight, states and logo size per the design.
• "Member for" is an h3 styled as h4, and the avatar link is named.

Tested on 87 pages of fresh Drupal CMS and Varbase installs: 0 Editoria11y findings, 0 serious axe WCAG 2.2 AA findings. One contrib finding remains on the login page (the Gin login show-password button), out of scope here.

AI-Generated: Yes

Remaining tasks

• ✅ File an issue
• ✅ Addition/Change/Update/Fix
• ✅ Testing to ensure no regression
• ➖ Automated unit/functional testing coverage
• ➖ Developer Documentation support
• ➖ User Guide Documentation support
• ✅ UX/UI designer responsibilities
• ✅ Accessibility and Readability
• ❌ 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 footer and header match the design. Nothing else changes visually.

API changes

• New optional label_context prop on the button component (new component version).

Data model changes

• N/A

Release notes snippet

• Give generic links screen-reader context, warn about new-tab links, and match the footer and header to the design.