Re-add HTML handling for summaries/excerpts

[pfefferle]

We removed the HTML handling for excerpts and summaries because Mastodon has not supported it. Now that Mastodon has merged this PR mastodon/mastodon#28629 I think it is fine to re-add the HTML handling.

Proposed changes:

Other information:

• Have you written new tests for your changes, if applicable?

Testing instructions:

• Go to '..'

Changelog entry

• Automatically create a changelog entry from the details below.

Changelog Entry Details

Significance

• Patch
• Minor
• Major

Type

• Added - for new features
• Changed - for changes in existing functionality
• Deprecated - for soon-to-be removed features
• Removed - for now removed features
• Fixed - for any bug fixes
• Security - in case of vulnerabilities

Message

Re-enabled HTML support in excerpts and summaries to properly display hashtags and @-replies, now that Mastodon supports it.

[Copilot]

Pull Request Overview

Re-enable HTML handling for excerpts and summaries now that Mastodon supports it.

• Restores the use of apply_filters('the_excerpt') in generate_post_summary to include HTML formatting.
• Applies HTML processing to all activity summary types in filter_activity_object.
• Cleans up obsolete comment blocks in both files.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
includes/functions.php	Removed commented-out code and replaced it with a direct call to \apply_filters('the_excerpt') along with an updated inline comment.
includes/class-link.php	Dropped the restricted type check and now processes HTML for all non-empty summaries.

Comments suppressed due to low confidence (2)

includes/functions.php:1226

• Consider sanitizing the output of apply_filters('the_excerpt', $content) using wp_kses_post() or a similar function to ensure only safe HTML is rendered and prevent potential XSS vulnerabilities.

return \apply_filters( 'the_excerpt', $content );

includes/functions.php:1226

• Add a unit or integration test to verify that HTML in excerpts is correctly passed through and that any sanitization behaves as expected.

return \apply_filters( 'the_excerpt', $content );

[obenland]

Nice!