### Stage 3: Archiving Changes
After deployment, create separate PR to:
- Move `changes/[name]/` → `changes/archive/YYYY-MM-DD-[name]/`
- Update `specs/` if capabilities changed
- Use `openspec archive <change-id> --skip-specs --yes` for tooling-only changes (always pass the change ID explicitly)
- Run `openspec validate --strict` to confirm the archived change passes checks