docs/ROADMAP.md replaces OPEN-QUESTIONS.md: what is built but not validated
(Linux, the real-vault differential, many editors at once), known
limitations, deferred work and open questions. CHANGELOG.md lists what
0.2.0 adds over 0.1.0. All crates move to 0.2.0, internal ones pinned
=0.2.0.

Test Plan:
bash scripts/check.sh: exit 0; relative-link check over README and docs:
0 broken; cargo publish --workspace --dry-run