docs: update CHANGELOG for v0.7.0 and v0.7.1

Add v0.7.0 (Unicode, key bindings, status bar, scroll, autocomplete)
and v0.7.1 (streaming, watchdog, markdown, URLs, syntax highlight,
Tab-activate, interrupt, bug fixes).

Add CHANGELOG update to release procedure in ROADMAP.org.

docs/ROADMAP.org

@@ -27,6 +27,7 @@ When a version's state changes (DONE → tested → released), update these loca
 3. ~~.env.example~ — update version references as needed
 4. ~lisp/core-transport.lisp~ — update the ~make-hello-message~ version string
 5. ~passepartout~ (bash entry point) — update version reference
+6. ~CHANGELOG.org~ — add new version entry with DONE items, LOGBOOK release date, and feature summaries
 
 On release:
 1. Tag the release on GitHub