.ssp: three additional fields the writers read

With these the .ssp carries every field the output writers read.
The two that were missing were both read by the sqlite search
writer, and one of them is needed by anything that wants to know
where an object sits in a segmented output:

- .segment_html_is / .segment_epub_is
  (tags.html_segment_anchor_tag_is, epub_segment_anchor_tag_is),
  the segment an object *belongs to*, as against .segment
  (in_segment_html), which is the segment a heading *opens* and is
  set on headings only: 32 of 36 headings and 0 of 109 paragraphs
  in the autonomous contract. Without them a reader cannot tell
  which segment a paragraph is in.
- .identifier for non-heading objects, the "a"~N series given to
  objects whose number is suppressed. A heading already carried it
  on its declaration line; every other object now carries it as a
  property, on the same condition, that it differs from the ocn.

The same two segment fields are added to the abstraction db
(segment_html_is, segment_epub_is) and to the cross-check test, so the
two serialisations stay level.

.ssp reference regenerated

output run (--text --latex --epub --html --curate) byte identical
to before the change, as it must be since no output writer reads
either artefact.

(assisted by Claude-Code)

0 files changed, 0 insertions, 0 deletions