Improve ImgSLI

A major release focused on smoother canvas interaction, sharper rendering, and a richer multi-magnifier workflow.

• Smoother zoom and panning in the main comparison canvas, with more responsive feedback during interactive movement.
• Cleaner image rendering with corrected alpha handling, so anti-aliased edges, magnifier circles, and overlays look crisp both on screen and in screenshots.
• Reworked multi-magnifier workflow: easier to add, hide, delete, and manage multiple magnifiers, each with its own color and settings.
• Optional automatic color assignment for new magnifiers and optional intersection highlighting while dragging capture areas.
• More consistent behavior across comparison modes, guide lines, capture rings, filename overlays, and exported images.
• Smoother live interactions: separators, splits, and magnifier dividers move without lag and stay in sync with the cursor.
• Better compatibility with Flatpak: removed the direct DBus notification path that caused integration issues.
• Updated in-app help to cover the expanded magnifier behavior and new canvas controls.

A major release consolidating months of deep architectural work and introducing significant new features.

• Hybrid CPU-GPU rendering: a new rendering engine capable of offloading work to the GPU via OpenGL shaders for dramatically improved performance on large images.
• Canvas architecture overhaul: the comparison canvas was fully rewritten for correctness and performance across all operating modes and edge cases.
• Native Qt widgets: all pop-up and overlay windows are now native Qt widgets, greatly improving Wayland compatibility.
• Canvas zooming and panning: the main comparison view can now be zoomed and panned interactively.
• Video editor improvements: the timeline was rewritten with keyframe-based model, aspect-ratio-correct thumbnails, and dynamic spacing.
• Plugin-based architecture for extensibility and a cleaner internal structure.

This release includes various improvements and bug fixes.

This is the most extensive architectural refactoring in the project's history, transitioning the entire application to a robust and modern Model-View-Presenter (MVP) pattern. This update establishes a new, stable foundation for future development and introduces a completely custom-built UI.

• Complete Architectural Overhaul: The codebase is now fully modular and based on the MVP pattern, significantly improving stability and maintainability. Many underlying bugs have been passively fixed as a result.
• New Custom UI: The third-party `PyQt-Fluent-Widgets` library has been removed and replaced with a custom-built set of "fluent-style" components. This removes GPL licensing constraints and gives the application a more unique design.
• Enhanced Image List Management: The image selection flyout is now a powerful two-panel manager with full drag-and-drop support for reordering and moving images between lists.
• New and Reimagined Dialogs: Introduced a dedicated, feature-rich Export dialog and a redesigned, easier-to-navigate Help window.
• Improved Caching: The caching system has been upgraded from two to three levels for even smoother performance during interactive use.
• Reduced Package Size: The removal of the external UI library has decreased the application's overall size on some platforms.