- Introduced comprehensive tests:
- `test_buffer_open_nonexistent_save.cc`: Save after opening a non-existent file.
- `test_buffer_save.cc`: Save buffer contents to disk.
- `test_buffer_save_existing.cc`: Save after opening existing files.
- Implemented `PieceTable::WriteToStream()` to directly stream content without full materialization.
- Updated `Buffer::Save` and `Buffer::SaveAs` to use efficient streaming via `PieceTable`.
- Enhanced editing commands (`Insert`, `Delete`, `Replace`, etc.) to use PieceTable APIs, ensuring proper undo and save functionality.
- Remove outdated `undo-state.md`
- Add two code quality/optimization reports that were used to guide previous work:
- `code-report.md` (optimization)
- `code-report-quality.md` (stability and code health)
- Add `themes.md`.
- Update undo system docs and roadmap.
- Normalize path handling for buffer operations, supporting tilde expansion and absolute paths.
- Introduce `DisplayNameFor` to uniquely resolve buffer display names, minimizing filename clashes.
- Add new commands: `ShowWorkingDirectory` and `ChangeWorkingDirectory`.
- Refine keybindings and enhance existing commands for improved command flow.
- Adjust GUI and terminal renderers to display total line counts alongside filenames.
- Update coding style to align with project guidelines.
