Introduces a 'visible' property to layers and updates all relevant logic to support toggling layer visibility. Adds visibility toggle icons to the layers panel using a new IconLoader utility, with SVG and fallback canvas icons. Updates rendering, selection, and batch preview logic to respect layer visibility. Also improves blend mode menu UI and ensures new/pasted layers are always added on top with correct z-index.
Introduces ShapeTool to allow users to define custom polygonal output areas by holding Shift+S and clicking to add points. The selected shape is used to crop and mask images and layers, and is visualized on the canvas. Updates Canvas, CanvasIO, CanvasInteractions, CanvasLayers, CanvasRenderer, and types to support shape-based output areas, including shape-aware import, export, and rendering logic.
Moved layer drawing logic into CanvasLayers._drawLayer and _drawLayers methods, replacing repeated rendering code in CanvasIO and CanvasLayers. This improves maintainability and ensures consistent handling of layer properties such as blend mode, opacity, rotation, and flipping. Also, fixed layer serialization to only generate imageId when missing, and ensured new layers have flipH/flipV set when created from matted images.
