Add user settings to control loading external content

[wofferl]

• Resolves: Support plain text and block external resources #1659
• Resolves: Add support for MRSS (media:content) extension #3212
• Resolves: Privacy options for the web frontend #3547

Summary

This PR adds settings to the web frontend to control loading external media.

It generally sets preload="none" on video and audio found in the article body.
Images are controlled with the settings and this can be show always, replace media with consent button or remove it at all.

Note:
This PR also added support for MRSS images, which are currently not shown. There can be redundancy with images from body or thumbnails and I disabled them generally if fulltext is enabled for the feed.
Thumbnails are now only displayed when media:content is audio or unknown mime type.
The default for theses images could also be set to 'never', so there is no change to the current state and users need to enable MRSS images by themselves.

Here an example of the consent buttons. It contains the domain and when an alt or title attribute is given a description. The type of media (img, iframe, etc) is shown in the button title.

These are the user settings:

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Changelog entry added for all important changes.

[codecov]

Codecov Report

❌ Patch coverage is 93.67816% with 11 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/components/feed-display/FeedItemDisplay.vue	90.98%	0 Missing and 11 partials ⚠️

📢 Thoughts on this report? Let us know!

[Copilot]

Pull request overview

This PR introduces user-configurable frontend settings to control whether external media (enclosure thumbnails/images and images/iframes inside article bodies) is loaded automatically, shown behind a consent button, or removed.

Changes:

• Add new media-related enums and a mediaOptions state/getter/mutation, initialized from server-provided initial state.
• Extend the settings dialog with new radio groups to configure media loading behavior.
• Update feed item rendering to (a) gate images/iframes behind consent UI and (b) set preload="none" for audio/video.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 12 comments.

Show a summary per file

File	Description
tests/javascript/unit/components/routes/Explore.spec.ts	Mock loadState for stable explore route unit tests.
tests/javascript/unit/components/modals/AppSettings.spec.ts	Add unit tests for new media settings controls.
tests/javascript/unit/components/feed-display/FeedItemDisplay.spec.ts	Add extensive unit tests for media gating/consent behavior and sanitization.
src/store/app.ts	Add mediaOptions to app state and initialize from initial state.
src/enums/index.ts	Introduce SHOW_MEDIA and MEDIA_TYPE enums.
src/components/modals/AppSettingsDialog.vue	Add “Media” settings section and persistence via mediaOptions.
src/components/feed-display/FeedItemDisplay.vue	Implement consent gating + sanitization of body HTML and enclosure rendering changes.
src/components/ContentTemplate.vue	Force FeedItemDisplay remount on item index changes (reset consent state).
lib/Controller/PageController.php	Provide initial state for mediaOptions from user config with defaults.
CHANGELOG.md	Add unreleased entries for the new settings and Media RSS image support.