Restrict the automatic `uninstall` legacy Codex sync fallback to homes
that have a legacy ownership manifest (`~/.codex/ecc/legacy-sync-state.json`).
Marker-only AGENTS.md files are no longer auto-detected as legacy installs,
so a normal `uninstall` will not silently modify user-owned instructions.
The explicit `--legacy-codex-sync` flag still handles marker-only and
manifest-backed cleanup.
Also:
- Track the AGENTS.md path in removedPaths when a marker block is removed.
- Refactor codex home resolution into a helper.
- Add regression tests for marker-only auto vs. explicit behavior.
Co-Authored-By: Paperclip <noreply@paperclip.ing>
