Fix Brazil election filter excluding a listed viewer's own id

[Pitchfork-and-Torch]

Bug

Brazil2026ElectionFilter treats a user as excluded when they are on the Electoral Court list and not in query.user_features.followed_user_ids.

That follow set is the social-graph following list. It never contains the viewer. So if the viewer is themselves a listed account, their own id is excluded.

That drops For You candidates that only surface the viewer:

• someone else retweets the viewer (retweeted_user_id == query.user_id)
• someone else quotes the viewer (quoted_user_id == query.user_id)
• a reply whose ancestor_users includes the viewer

SelfTweetFilter already removes the viewer's own posts. This hole is the amplification / thread-context path.

SelfReplyChainFilter already inserts query.user_id into its allowed set for the same reason. This filter did not.

Existing tests used ScoredPostsQuery::default() (empty follows, user_id == 0) and never covered the follower exception or self-id.

Fix

Insert query.user_id into the allowed set before should_remove.

is_excluded_author is unchanged: listed and !followed_user_ids.contains. Unfollowed listed authors, retweets, quotes, and ancestors still drop.

Tests

• listed author the viewer follows is kept; a different unfollowed listed author still drops
• retweet / quote / listed ancestor of the viewer are kept
• the same three shapes still drop when the listed id is not the viewer and is not followed
• reply is kept when the viewer follows the listed ancestor

Lane: home-mixer/filters/brazil_2026_election_filter.rs only. Based on xai-org/x-algorithm main (c65aa179).