feat: add content contracts and document verification

release: 1.9.4

release: 1.9.3

release: 1.9.2

release: 1.9.1

release: 1.9.0

release: 1.8.0

release: 1.7.4

release: 1.7.3

Ship the accumulated work since V1.7.2 and bootstrap the update check.

Highlights since the last tag: tighter resume project spacing across
en/zh/ko, a nine-tile demo gallery in the README with the Mole and
Waza one-pagers, real Mole v1.7.1 changelog and recommendation-letter
demos, a unified editorial header signature, native list markers in
place of the en-dash bullet, and the #30 thin-border lint fix.

This is also the first release to carry scripts/check-update.sh, so it
acts as the bootstrap: installs of 1.7.3 gain the daily checker, and
every release after this one will surface the new version to them.