When someone on the fediverse mentions or replies to the streamer, posts a system message in chat showing the poster's avatar, display name, handle (linked to their profile), and the post text (linked to the original).
Demonstrates: the typed @plugin.on_fediverse_mention / @plugin.on_fediverse_reply handlers, owncast.chat.system(html) for posting an HTML system message (no user identity), and the discipline of escaping every untrusted field before inserting it into rendered HTML (the plugin ships its own escape_html / safe_url helpers). The plugin subscribes to two of the seven events gated by fediverse.inbound. It does not handle follows, likes, reposts, quotes, or raw activities.