feat(fediverse): inline @mentions in posts (link + notify)
Typing @user@host in a post now federates as a real Mastodon-style mention: the
handle is linked to the actor, added to the note's Mention tags + cc, and the note
is delivered to the mentioned person's inbox so they're notified — even if they
don't follow the site. Mirrors the existing reply-mention flow (which resolved
mentions but posts didn't). On-site the post text is unchanged for now.
- src/services/ActivityPubService.js — buildNote emits Mention tags + adds the
mentioned actors to cc (from already-linked content); deliverCreate/deliverUpdate
resolve inline mentions at send time (WebFinger), link the note content, and add
the mentioned inboxes to the delivery set (so a mention reaches non-followers too).
- test/mentions.test.js — Mention tag shape, cc addressing, and the no-mention no-op.
- CHANGELOG(.nl/.de).md — "Mention people in a post" under Unreleased.
Co-Authored-By: Claude <noreply@…>