fix: hide suspended account

internal/repository/mention_repo.go

@@ -34,6 +34,8 @@ func (r *MentionRepo) Suggest(ctx context.Context, viewerID, q string, limit, of
 		       END AS rank
 		FROM users u
 		WHERE u.id <> $1
+		  -- A suspended account can't be @mentioned into a post.
+		  AND u.banned_at IS NULL
 		  AND ($2 = '' OR u.name ILIKE $3 OR u.handle ILIKE $3)
 		ORDER BY rank, u.name, u.id
 		LIMIT $4 OFFSET $5`,