odt: office:meta from the document, not the run

Three faults in four lines of the odt metadata.

meta:creation-date and dc:date were taken from generated_time, the run's
own clock, so two runs over unchanged markup produced different odt
bytes. They now carry the document's own instant, so an odt is a
function of its source. That was the last clock stamp in any writer:
every output format is now reproducible.

generated_time is a human-readable run stamp, of the form
"2026-9-17 [38/3] 18:39:35", with unpadded numbers and an iso week in
brackets. It is not a valid xsd:dateTime, which is what ODF asks for in
both of those fields, so what was written there was malformed as well as
unstable.

dc:language now carries the document's own language tag.

The instant is doc_matters.modified_utc, moved there from epub3.d
in this commit: epub3 needs the same value for its dcterms:modified,
and one definition cannot drift from the other. generated_time now
has no caller and is left in place.

(assisted by Claude-Code)

0 files changed, 0 insertions, 0 deletions