- 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.
- Created `piece-table-migration.md` outlining the steps to transition from GapBuffer to a unified PieceTable architecture.
- Included phased approach: extending PieceTable, Buffer adapter layer, command updates, and renderer changes.
- Detailed API changes, file updates, testing strategy, risk assessment, and timeline for each migration phase.
- Document serves as a reference for architecture goals and implementation details.
- Added `PieceTable` class for efficient text manipulation and implemented core editing APIs (`Insert`, `Delete`, `Find`, etc.).
- Integrated `PieceTable` into `Buffer` class with an adapter for rows caching.
- Enabled seamless switching between legacy row-based and new PieceTable-backed editing via `KTE_USE_BUFFER_PIECE_TABLE`.
- Updated file I/O, line-based queries, and cursor operations to support PieceTable-based storage.
- Lazy rebuilding of line index and improved management of edit state for performance.
