- Introduced support for multiple windows, sharing the primary editor's buffer list.
- Added `GUIFrontend::OpenNewWindow_` for creating secondary windows with independent dimensions and input handlers.
- Redesigned `WindowState` to encapsulate per-window attributes (dimensions, renderer, input, etc.).
- Updated input processing and command execution to route events based on active window, preserving window-level states.
- Enhanced SDL2 and ImGui integration for proper context management across multiple windows.
- Increased robustness by handling window closing, resizing, and cleanup of secondary windows without affecting the primary editor.
- Updated documentation and key bindings for multi-window operations (e.g., Cmd+N / Ctrl+Shift+N).
- Version updated to 1.8.0 to reflect the major GUI enhancement.
- Added `QtFrontend`, `QtRenderer`, and `QtInputHandler` for Qt-based UI rendering and input handling.
- Implemented support for theming, font customization, and palette overrides in GUITheme.
- Renamed and refactored ImGui-specific components (e.g., `GUIRenderer` -> `ImGuiRenderer`).
- Added cross-frontend integration for commands and visual font picker.
