v6.0.0

Major Changes

• #171 c561739 Thanks @rexxars! - Require Node.js 22.12 or later, and drop the legacy main and module fields

  The package has been ESM-only for a while, but still carried main and module entry points for
  resolvers that predate exports. Those are gone, so the package resolves through exports only.

• #171 c561739 Thanks @rexxars! - nestLists() now nests every list as deeply as its level says it is

  List items can start at a level deeper than 1, and can skip any number of levels at a time.
  nestLists() previously ignored both, so a level 3 item could end up as a list nested only one
  level deep, and items that later returned to a shallower level could fail to rejoin the list they
  belonged to and be emitted as a separate sibling list instead.

  The levels that were never authored are now generated, so nesting depth always matches level.
  A generated list holds an empty list item in html mode, since HTML can only nest a list inside a
  list item, and holds nothing but the deeper list in direct mode.

  This changes the output of nestLists() for any input where a list starts deeper than level 1 or
  skips a level, and therefore changes the rendered output of anything built on it.