Improve <书社:apply-attributes>, @书社:archived-as

- `<书社:apply-attributes>` should not prevent H·T·M·L from wrapping.
  Note that the H·T·M·L wrapper is still not
  `<书社:apply-attributes>`‐aware; it will _not_ seek into the wrapped
  contents to search for attributes to pull upwards to the root
  element. This could probably be improved.

- `@书社:archived-as` can now be applied to `<书社:link>` and will be
  passed down to any embedded contents.

- `@书社:archived-as` will not be deleted during attribute application
  onto the root element; it now ensures there is a nonroot, nonarchive
  ancestor. This is required because archive children are processed
  into a separate document prior to application.

  An alternative approach might be to wrap archive children in a
  `<书社:archive>` element before application and then strip it after,
  but this is a fair bit of added work for little benefit. It’s a fair
  question whether removing invalid `@书社:*` attributes like this is
  even a good practice—invalid `<书社:link>` elements are maintained,
  in contrast.