fix(changelog): render the commit body, not just the subject

Symptom: the mirrored CHANGELOG.md (and the page) showed one-line commit
summaries while README promises "every shipped fix, symptom -> cause -> fix ->
verified". A reviewer measured the gap from the public mirror and could only
conclude the claim overpromised.

Cause: scripts/build-changelog.py:59 formatted commits with %s only; %b was
never read, so the verification prose every fix commit carries (5b55af9 is a
typical one) was discarded before rendering. The MD writer then replaced every
tag with a backtick, so nothing richer could have survived anyway.

Fix: read %b with a %x02 terminator (line-based parser, multi-line body), split
it into paragraph/bullet blocks capped at 900 chars with a visible marker, and
render it twice from one source: as a native <details> per item on the page
(its renderer already assigns item HTML, so no JS change; CSS injected once
behind a sentinel) and as nested bullets under the line in CHANGELOG.md. The
"every build" gap note and the page dek were rewritten to describe what the
file now contains.

Verified: page 100 details render, first opens 23 -> 232 px with 3 paragraphs,
no horizontal overflow, island parses (83 entries); two consecutive runs are
byte-identical for CHANGELOG.md; the double-escape bug this surfaced (code
spans shipped as &amp;lt;sha&amp;gt;) is fixed and grep for &amp;lt; is 0.

0 files changed, 0 insertions, 0 deletions