safe-revertlisted

# /safe-revert This is deliberately conservative: it only ever reverts **one commit at a time**, via `git revert` (which adds a new commit undoing the last one and keeps full history), never `git reset --hard` or anything that rewrites or discards history. Running it again reverts one step further back if needed. ## Steps 1. If there's no `.git` history yet, or nothing to revert, say so and stop. 2. **Preview before acting.** Show the user the most recent commit: its message (`git log -1 --oneline`) and a summary of what it touched (`git show --stat HEAD`). Explain in plain language what reverting it will undo — e.g. "this will undo marking day 4 done and roll `state.json` back to day 4 being current again." 3. **Ask for explicit confirmation** before doing anything. Don't proceed on an ambiguous or implied "yes" — get a clear go-ahead. If the user declines or seems unsure, stop without changing anything. 4. Once confirmed: `git revert --no-edit HEAD`. This creates a new commit that undoes the last one; nothing is force-rewritten or destroyed, so the original commit is still there in history if they change their mind later (they'd need to ask for that explicitly — this command only ever moves forward-via-revert, not through raw `git reset`). 5. Run `python3 scripts/validate_state.py` on the result to confirm the reverted state is still schema-valid (it should be, since it's returning to a previously-committed-and-validated state, but