Tell screen reader users that the Listen on links open in a new tab

Problem/Motivation

The "Listen on" links on an episode page (YouTube Music, Apple Podcast, Overcast, Spotify) point to other sites, and the External Links module opens them in a new tab at run time. Their text is only the platform name, so a screen reader user is not told. Editoria11y flags each one with "linkNewWindow: is opening a new window expected?" (four alerts on every episode page, on a stock English install). The Share component already says "(opens in a new tab)" in hidden text, so these links are the odd ones out.

Steps to reproduce

1. Log in as a user who can see Editoria11y and open any podcast episode, for example /podcasts/last-call/no-straight-walls.
2. Open the checker panel: four "new window" alerts on the Listen on links.

Proposed resolution

In components/molecules/podcast-platforms/podcast-platforms.twig, add the visually hidden translatable text "(opens in a new tab)" after the label of every link whose URL starts with http. Internal links such as the RSS feed are left alone.

Not covered: Editoria11y's "embedAudio" alert on the audio player is a manual check ("is an accurate transcript provided?") that an editor dismisses; the page has a transcript section.

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

• Visually hidden text after each external listen link. Nothing changes on screen.

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• The "Listen on" links on an episode page tell screen reader users that they open in a new tab.

AI-Generated: Yes. Drafted and tested with Claude Code, reviewed by the contributor.