Newlines should be preserved when federating code blocks

[mediaformat]

Federated posts containing code bocks, have new lines removed, resulting in poor legibility.

The preg_replace here is the likely culprit:

wordpress-activitypub/includes/transformer/class-post.php

Line 542 in df2e21c

$content = \preg_replace( '/[\n\r\t]/', '', $content );

Example: https://join.piefed.social/2025/11/22/reducing-piefeds-dependence-on-cloudflare/