- Added main application class `SpriteEditorApp` with layout setup.
- Created menu bar with placeholder options.
- Implemented `BottomToolbarView`, `LeftSidebarView`, `MainEditorView`, `RightSidebarView` with basic UI elements.
- Added dialog classes for `ExportSettingsDialog` and `FlipbookCreatorDialog` to manage export settings and flipbook creation.
- Introduced support for loading and displaying images in the flipbook creator.
- Established a structure for handling sprite sheet composition and preview rendering.
