- 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.
- Replace header include guards with `#pragma once` and perform minor optimizations.
- Replaced traditional include guards with `#pragma once` for simplicity and to reduce boilerplate in all headers.
- Improved CLI line number handling with clamping and error messaging.
- Enhanced `chdir` error handling for macOS GUI builds.
- Removed redundant logic for GUI builds.
- Adjusted font constructor and registry to handle `const` data pointers consistently.
- Add visual file picker for GUI with toggle support.
- Introduce `GUIConfig` class for loading GUI settings from configuration file.
- Refactor window initialization to support dynamic sizing based on configuration.
- Add macOS-specific handling for fullscreen behavior.
- Improve header inclusion order and minor code cleanup.
