ocda: fixed inverted object_number_off on body paragraphs

ssp: make use of curly braces (code-style)

(assisted by Claude-Code)

--+# clears dummy_heading_multiple_objects, fixed

until fix, following any ---# ... --+# block every ~# object in
the document was marked dummy_heading, (and the output generators
that honour that flag suppressed its text: so ~# behaved as -#.
One line added to correct the --+# branch.

~# suppresses the object's number only, content is still shown.
-# is for a heading introduced solely to segment an output:
object number suppressed and the heading text omitted from the
body where the output format allows, the toc entry kept. Both were
already correct in isolation; only the leaked block flag broke ~#.

(assisted by Claude-Code)

fix to --abstraction/.ssp: fix document structure, representation
parent, ancestors, children. Make parent_ocn, the marked-up and
collapsed ancestor arrays, and the children correctly represent
the document structure. fixed

(assisted by Claude-Code)

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01836BxBb8LvVKJ8sBg7Dx6U

for document abstraction and its .ssp output, removed the
requirement of including --abstraction & --serial flags to produce
correct output (for: .dom_status, .dom_status_collapsed &
.last_descendant)

- meta_processing_xml_dom() includes show_abstraction, so --pod2
  and --show-abstraction run the dom pass; last_descendant is
  derived from that pass via after_doc_get_descendants()

The accumulators are now verified as eight wide locals of
docAbstraction(), so each document starts clean and no two threads
share one.
- bug: the four dom accumulators were template scope (shared) and
  nine wide, while their end of document reset was eight wide, so
  the first document of a run differed from the rest and parallel
  runs raced on one buffer, (which also mis-nested epub toc_nav)

test/ reference .ssp regenerated: accelerando only, trailing zero
dropped.
test-abstraction-ssp.sh now runs parallel and diffs output against
a serial run.

(assisted by Claude-Code)

Assumed that headings do not include images, obj_digest() looked
for images only in the non-heading branch, however, the markup
does not forbid one, and an object type left out of the scan
carries neither digest nor .ssp record, silently.

Open Issue: image_list, which drives pod bundling and the @doc_has
images count, is gathered only from para objects (and only the
first image of each), so an image in a heading or in a block body
is recorded in the abstraction but not bundled.

(assisted by Claude-Code)

Count them over the assembled body objects, (the body alone).

Previously dochas["inline_links"], ["inline_notes"] and
["inline_notes_star"] were initialised and read but never
incremented, so @doc_has reported 0 inline links and 0 notes for
every document while the block counters (codeblock, poem, group,
block, quote, table) were counted. create_abstraction_db.d records
the same values as document metadata.

(assisted by Claude-Code)

every object with an .image record should now carry the images
flag.

Previously DocObj_Has_.images was read but never written anywhere
in the tree, so no object carried it: .ssp emitted has_images = 0
for every object of every document.

(assisted by Claude-Code)

For image digests cache file read & hash, one read per image
file

Fix issue: images referenced from several objects were read and
hashed once per reference.

  [as an example in the sisu-manual sm_tux.png accounts for 6 of
  the document's image records (12 across the sample set), each
  of them a fresh read of the same bytes, and source_pod.d hashes
  the file again for digests.txt.]

Memoise on the full path within safeComputeHashAndSize. static is
thread-local in D, so documents processed in parallel each get
their own cache and no synchronisation is involved. Files are not
expected to change during a run.

Output is unchanged: identical .ssp output. (An image that is
missing or unreadable now warns once to stdout rather than once
per reference).

(assisted by Claude-Code)

Complete image file digest identity record: add
px:<width>x<height> to the .ssp image record, read from the
image file header (imageformats.read_image_info, no decode):

  .image: won_benkler_2_1.png sha256:5BA4...D128 bytes:93861 px:420x342

(The w##h## dimensions in the markup are display dimensions, not the
file's: they are author set, or where given as w0h0 are derived by
_image_dimensions and capped to a maximum display width, and they
become the width/height attributes of the output format image display).

(assisted by Claude-Code)

image digest: record missing or unreadable image, do not abort

safeComputeHashAndSize() open image with guard, so a document
naming an image absent from media/image/ throws
ErrnoException out of the abstraction stage.

as with _image_dimensions() (which warns and continues where issue
with image) warn to stdout and record the fact in the abstraction:

  .image: ffa.png missing:true

the abstraction would now state that the object embeds an image it
could not read, rather than the .ssp resemble one produced from a
complete pod. The sha256 summary line marks the same case
MISSING OR UNREADABLE.

(assisted by Claude-Code)