[rmdes]

Refs #843.

Likes and reposts are syndicated as native favourites and reblogs, but only when the status is on the syndicator's own server. Liking a status on any other instance is skipped, and endpoint-syndicate reports it as "did not return a URL". Without the ActivityPub plugin, that's the only route a like has to the fediverse, so for most likes nothing happens.

Replies already resolve statuses on other servers (resolveRemoteStatus, #927). This uses the same step for likes and reposts:

• postFavourite and postReblog take the status ID from the URL when the status is on this server, and otherwise resolve it with v2/search (resolve: true).
• post() no longer drops likes and reposts of other servers' URLs up front.
• A repost with content (a quote status) is syndicated when the reposted URL resolves to a status.
• URLs that don't resolve to a status (a blog post, say) are still not syndicated, so defaults are unchanged and there are no new options.

Opt-in statuses for likes and reposts of URLs that aren't statuses (syndicateExternalLikes / syndicateExternalReposts) can follow separately, depending on the discussion in #843.

Tests

• Unit tests for favouriting and reblogging a status on another server, the same through post(), quote statuses of a remote status, and skipping URLs that don't resolve.
• The two existing "doesn't post a favourite/repost of a URL" tests now use the mocked unresolvable URL, since every like and repost now searches first.
• Syndicator, endpoint-syndicate and endpoint-share syndication tests pass (73/73, Node 24.17).