Replaces all uses of alert() with showErrorNotification or showSuccessNotification for improved user experience and consistency. Refactors canvas creation to use the createCanvas utility function across multiple files, reducing code duplication and improving maintainability. Also updates layer ID generation to use generateUUID.
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.
Dariusz L