Untrack TODO.md, RELEASING.md, RELEASE_NOTES.md, ideas/ and
docs/CLAUDE_PROPER_OBJECT_REGISTRATION_PLAN.md -- internal planning and
agent notes with no reason to be published. Files stay on disk locally.
Replace remaining absolute machine paths in docs with relative ones
(one referenced a separate private project), and swap decorative emoji
for ASCII markers.
README: lead with the no-longer-actively-developed notice.