- Updated `Refresh` command to clear the mark when no active prompt, search, or visual-line mode is present.
- Added a new unit test verifying mark-clearing behavior for `Ctrl-G` (mapped to `Refresh`).
- Bumped version to 1.6.3 in `CMakeLists.txt`.
- Introduced SwapManager for sidecar journaling of buffer mutations, with a safe recovery mechanism.
- Added group undo/redo functionality, allowing atomic grouping of related edits.
- Implemented `SwapRecorder` and integrated it as a callback interface for mutations.
- Added unit tests for swap journaling (save/load/replay) and undo grouping.
- Refactored undo to support group tracking and ID management.
- Updated CMake to include the new tests and swap journaling logic.
