Search boards and items

Two searches in one. Board titles are matched across every board the token can see, paged, the way the dashboard search works. Item text is searched the way Mida's own board search works: q is a regular expression (a plain string when it does not compile), matched line by line against each item's content, label matches first. Item search opens boards, so it is bounded: one board with boardId, otherwise the most recently updated boards up to a ceiling, and the answer says when the ceiling was hit. It reads saved pages; an edit nobody has saved yet is not searchable.